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Physica Scripta

Welcome to the Physica Scripta Best of 2011 articles collection

ISSN 0031-8949 Physica Scripta


cle in the

045001–048401

c circuits

Vol 84, No 4

potentials:

Volume 84 Number 4 October 2011 A journal of the Royal Swedish Academy of Sciences published by IOP Publishing

Featured in this issue

Comments on Astrophysics and Cosmology

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As Editor-in-Chief of Physica Scripta, I am pleased to present this compilation of journal highlights selected on the basis of downloads and citations to represent the most insightful, innovative and progressive work published in the journal during 2011.

antum system

nments

The collection is intended to give readers a sample of the journal content and is not intended to be a definitive list of ‘best articles’. The full text for each article presented is freely available without subscription until the end of 2012.

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October 2011

on inside back cover)

12/10/2011 10:14

Impact Factor

0.985* *As listed in the 2010 ISI Journal Citation Reports®

Fast Publication

25 days Average acceptance-toonline-publication time

Abstracts are ordered by PACS code, and have been chosen from each subject area to provide an overview of the broad scope covered in the journal. Several abstracts from Comments sections and from two Topical Issues published during 2011 have also been included. Physica Scripta has shown a continuous growth in terms of submitted manuscripts, continuing throughout 2011, and the journal has become an important physics publication because of the high editorial standards. Editorial Board members are active researchers from top institutions, and all submitted papers are subject to rigorous peer review. Reviewers are encouraged to provide constructive feedback that can provide authors with assistance when improving their manuscripts. The final acceptance/rejection decision remains the responsibility of the Editors and currently about two out of three submissions to the journal are rejected. Summing up, the editors of Physica Scripta are active researchers within their topics and ensure expert constructive feedback is provided to the scientific community. I hope that you enjoy the collection and find the articles of great interest as well as beneficial to your own work.

Cover image: Spinning phenomena and energetics of spherically pulsating patterns in stratified fluids. Top: contour plots of the invariant solution for the stream function; middle: spinning phenomena; bottom: effects of nonlinearity on the spinning phenomenon (adapted from R N Ibragimov and M Dameron 2011 Phys. Scr. 84 015402; artistic impression by Frédérique Swist).

Prof. Roger Wäppling Editor-in-Chief, Physica Scripta

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rope

Physica Scripta

244 185 Full-text downloads in 2011

Published on behalf of the Physical Societies of the Nordic Countries by IOP Publishing and the Royal Swedish Academy of Sciences, Physica Scripta offers researchers a very flexible publishing service, making the journal an excellent choice for all theoretical and experimental physics. Journal scope Physica Scripta is an international journal for experimental and theoretical physics, comprising strong components of atomic, molecular and optical physics, plasma physics, condensed matter physics and mathematical physics. The journal publishes Comments in six different sections and maintains a programme of Topical Issues alongside the regular 12 issues a year. Physica Scripta celebrated its 40th anniversary in 2010 and continues to grow in strength, content, prestige and distribution.

Geographical distribution of full-text downloads

North America 21%

UK 4%

Western Europe 19% Eastern Europe 4%

Asia 32%

Middle East 6% Africa 1% Central/South America 3%

Australasia 1%

Geographical distribution of paper submissions

North America 6% Asia 32%

UK 1%

Western Europe 6% Eastern Europe 7%

Asia 48%

Middle East 21% Africa 9%

Australasia 1%

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Central/South America 2%

Australasia 0%

Physica Scripta

Managing Editor

Publish your research in Physica Scripta

Roger Wäppling Uppsala University, Sweden

Physica Scripta accepts a number of different types of papers.

Comments Editors

Comments

Comments on Condensed Matter Physics (CCMP) L Dobrzynski Cardinal Stefan Wyszynski University and National Centre for Nuclear Research, Poland

•Atomic, Molecular and Optical Physics (CAMOP) •Condensed Matter Physics (CCMP) •Nuclear and Particle Physics (CNPP) •Plasma Physics and Controlled Fusion (CPPCF) •Astrophysics and Cosmology (CAC) •Facililties and Research Projects (CFRP)

Comments on Atomic, Molecular and Optical Physics (CAMOP) H H Stroke New York University, USA H Linnartz Leiden Observatory, The Netherlands

Comments on Nuclear and Particle Physics (CNPP) U Heinz Ohio State University, Columbus, USA J Räisänen University of Helsinki, Finland Comments on Plasma Physics and Controlled Fusion (CPPCF) G Brodin Umeå University, Sweden J Heikkinen VTT Processes, Finland S Abarzhi University of Chicago, USA

Comments describe the current thinking of leading researchers on outstanding problems. This may include discussion of open questions, questions that recent work has apparently closed, important new applications, new theoretical and experimental approaches, and predictions of future developments. Intended to bridge gaps in readers’ knowledge and provide insight into problems, methods and results in different areas of physics, six sections are available encompassing the whole of physics:

Each Comments section has its own designated Editor. Authors are encouraged to write articles of 2500–6000 words in length. Care should be taken to ensure that the article is accessible for non-experts and graduate students. Comments on controversial topics are desirable, provided that the author fairly represents all sides of the community. Topical Issues Volumes, published separately from the regular journal issues, contain invited presentations and/or poster contributions from international conferences highlighting cutting-edge research across key areas of physics. Research papers Reports of original research not normally more than 8500 words in length.

Comments on Astrophysics and Cosmology (CAPC) B Gustafsson Uppsala University, Sweden Comments on Facilities and Research Projects (CFRP) L Thorlacius Science Institute, University of Iceland, Iceland

Journal team Our dedicated team at IOP Publishing is here to ensure that the peer-review process runs as smoothly as possible for our authors.

Publisher Graeme Watt

Production Editor Benjamin Skuse

Publishing Administrator Elaine Packer

Publishing Administrator John Fryer

Marketing Executive Emma Watkins

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Physica Scripta

Physica Scripta is published by IOP Publishing on behalf of: •The Royal Danish Academy of Sciences and Letters in cooperation with the Danish Physical Society •The Delegation of the Finnish Academies of Sciences and Letters in cooperation with the Finnish Physical Societies •The Icelandic Scientific Society in cooperation with the Icelandic Physical Society •The Norwegian Academy of Science and Letters in cooperation with the Norwegian Physical Society •The Royal Swedish Academy of Sciences in cooperation with the Swedish Physical Society

Editorial Board S Mannervik University of Stockholm, Sweden M Manninen University of Jyväskylä, Finland H L Pécseli University of Oslo, Norway

D Röhrich University of Bergen, Norway L Thorlacius Science Institute, University of Iceland, Iceland

External Editors L J Curtis University of Toledo, USA L Dobrzynski Cardinal Stefan Wyszynski University and National Centre for Nuclear Research, Poland J Javanainen University of Connecticut, Storrs, USA M Man’ko Lebedev Physical Institute, Russia S Mannervik University of Stockholm, Sweden K Mork Norwegian University of Science and Technology, Norway

R Nieminen Helsinki University of Technology, Finland H L Pécseli University of Oslo, Norway J J Rasmussen Risø National Laboratory, Denmark D Röhrich University of Bergen, Norway L Stenflo Umeå University, Sweden M Y Yu Zhejiang University, China

About IOP Publishing IOP Publishing provides publications through which leading-edge scientific research is distributed worldwide. Since launch we have expanded rapidly to become one of the leading international STM publishers. We have a global reach, with offices in Philadelphia, Washington DC, Mexico City, Munich, Moscow, St Petersburg, Wroclaw, Beijing and Tokyo, as well as Bristol and London in the UK. IOPscience is IOP Publishing’s electronic platform providing access to more than 130 years of leading scientific research and hosting over 350 000 articles dating from 1874 to the present day. For authors, IOPscience provides a compelling opportunity to publish work that will achieve visibility and status amongst the scientific community. IOP Publishing is central to the Institute of Physics, which was established in 1874. The Institute of Physics is a not-for-profit society and any surplus from IOP Publishing goes to support science through the activities of the Institute. Physics is an international endeavour and the Institute aims to promote and support physics in furthering scientific knowledge and providing economic and social benefits both in the UK and Ireland as well as internationally – especially in the developing world.

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Physica Scripta

Contents General Delay-improved signal propagation in globally coupled bistable systems

11

J H Yang and X B Liu

Amplification of weak signals via the non-adiabatic regime of stochastic resonance in a bistable dynamical system with time delay

11

Lu-Chun Du and Dong-Cheng Mei

Electromagnetic potentials without gauge transformations

11

A Chubykalo, A Espinoza and R Alvarado Flores

Coulomb screening of 2D massive Dirac fermions

11

Jia-Ning Zhang

Resolution of the Klein paradox

12

A D Alhaidari

On eigenvalue problems in quantum mechanics

12

Aparna Saha, Umapada Das and B Talukdar

Accurate analytic approximation to the nonlinear pendulum problem

12

M Turkyilmazoglu

The Schmidt number as a universal entanglement measure

12

J Sperling and W Vogel

Nuclear physics Characteristics of multiplicity distribution of target fragments in forward and backward hemispheres in high-energy nucleus–nucleus interactions

13

Dipak Ghosh, Argha Deb and Swarnapratim Bhattacharyya

Nuclear structure of the neutron-rich 140–148Ba isotopes

13

A R H Subber and Falih H Al-Khudair

Atomic and molecular physics The mechanical, electronic structure and thermodynamic properties of B2-based AgRE studied from first-principles

13

Xiaoma Tao, Hongmei Chen, Xingxiu Li, Yifang Ouyang and Shuzhi Liao

Electromagnetism, optics, acoustics, heat transfer, classical mechanics and fluid dynamics U-shaped multi-band negative-index bulk metamaterials with low loss at visible frequencies

14

Kun Song, Quanhong Fu and Xiaopeng Zhao

Propagation of shock waves in a viscous medium

14

Harish C Yadav and R K Anand

Optimization of the bubble radius in a moving single bubble sonoluminescence

14

Mona Mirheydari, Rasoul Sadighi-Bonabi, Nastaran Rezaee and Homa Ebrahimi

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Mixed convection boundary-layer flow about an isothermal solid sphere in a nanofluid

14

L Tham, R Nazar and I Pop

Generation of continuous-variable entanglement in a three-level system coupled with a parametric oscillator

15

Yong-Hong Ma

Power-flow formulation of a ray approach to the modelling of inhomogeneous waves

15

M Tereshchenko, F Castejón, S Pavlov and A Cappa

Physics of gases, plasmas and electrical discharges Nonplanar ion-acoustic solitary waves in electron–positron–ion plasmas with electrons following a q-nonextensive distribution 15 P Eslami, M Mottaghizadeh and Hamid Reza Pakzad

The 3+1 dimensional Kadomtsev–Petviashvili Burgers’ equation in non-uniform dusty plasmas

15

Li-Ping Zhang, Ju-Kui Xue and Li-Hua Yuan

Experimental and theoretical studies of the direct-current breakdown voltage in argon at micrometer separations

16

M Klas, Š Matejcˇík, B Radjenovic´ and M Radmilovic´-Radjenovic´

Electron acoustic solitary waves with kappa-distributed electrons

16

S Devanandhan, S V Singh and G S Lakhina

Dust acoustic instability with Lorentzian kappa distribution

16

Sanqiu Liu and Jing Li

Instabilities in strongly coupled ultracold neutral plasmas

16

M Rosenberg and P K Shukla

Influence of gas pressure on the structure and dynamics of dust rotation in magnetized dusty plasmas

16

F Huang, Y H Liu, M F Ye and L Wang

Condensed matter: structural, mechanical and thermal properties Electrical properties of the double perovskite oxide Ho2CuZrO6

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The effect of heating conditions on the properties of nano- and microstructured Ni–Zn ferrite

17

D K Mahato, Alo Dutta, Nishant Kumar and T P Sinha

A Sutka, K A Gross, G Mezinskis, G Bebris and M Knite

Structural and dielectric properties of Cr-doped Ni–Zn nanoferrites

17

S Nasir, M Anis-ur-Rehman and Muhammad Ali Malik

Structural, electrical and magnetic studies of nickel–zinc nanoferrites prepared by simplified sol–gel and co-precipitation methods

18

S Nasir and M Anis-ur-Rehman

Negative differential conductivity in bilayer graphene controlled by an external voltage and in the presence of a magnetic field 18 N N Yanyushkina, M B Belonenko and N G Lebedev

Pseudopotential calculation of the bulk modulus and phonon dispersion of the bcc and hcp structures of titanium

18

Mahmoud Jafari, Niloofar Zarifi, Maryam Nobakhti, Atefeh Jahandoost and Maryam Lame

Effect of substrate temperature in the synthesis of BN nanostructures

18

M Sajjad, H X Zhang, X Y Peng and P X Feng

The fabrication, characterization and electrochemical corrosion behavior of Zn-TiO2 composite coatings M K Punith Kumar, T V Venkatesha, M K Pavithra and A Nithyananda Shetty

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Physica Scripta

The structural, elastic and vibrational properties of the DyX (X=P, As) compounds

19

H Özıs¸ık, Y Ö Çiftci, K Çolakogˇlu and E Deligöz

Physical and chemical properties of a Ga-doped ZnO crystal

19

Arvids Stashans, Katia Olivos and Richard Rivera

Condensed matter: electronic structure, electrical, magnetic and optical properties A carbon nanotube-based pressure sensor

19

Kh S Karimov, M Saleem, Z M Karieva, Adam Khan, T A Qasuria and A Mateen

Specific heat and magnetization studies of RMnO3 (R=Sm, Eu, Gd, Tb and Dy) multiferroics

20

The photoluminescence and magnetism of nitrogen-implanted ZnO

20

N Pavan Kumar, G Lalitha and P Venugopal Reddy

CM Liu, X Xiang, Y Zhang, HQ Gu, Y Jiang, M Chen and XT Zu

First-principles study of structural, elastic, electronic, lattice dynamic and optical properties of XN (X=Ga, Al and B) compounds under pressure

20

M Fatmi, B Ghebouli, M A Ghebouli and Z K Hieba

Electric field effects on the intersubband optical absorptions and refractive index in double-electron quantum dots

20

Liangliang Lu and Wenfang Xie

Nonlinear transport through ultra-narrow zigzag graphene nanoribbons: non-equilibrium charge and bond currents

21

Hosein Cheraghchi

Magnetic and transport properties of chemical solution deposited (100)-textured La0.7Sr0.3MnO3 and La0.7Ca0.3MnO3 nanocrystalline thin films

21

Giray Kartopu, Orhan Yalçin and A Serdar Demiray

Improvement in the luminous efficiency of MEH-PPV based light emitting diodes using zinc oxide nanorods grown by the electrochemical deposition technique on ITO substrates

21

Rohini B Gupta, Jitender Kumar, Devinder Madhwal, Inderpreet Singh, I Kaur, L M Bhardwaj, S Nagpal, P K Bhatnagar and P C Mathur

Effect of pressure on the global and local properties of cubic perovskite crystals

22

Tarik Ouahrani, I Merad-Boudia, H Baltache, R Khenata and Z Bentalha

Interdisciplinary physics and related areas of science and technology Role of donor–acceptor domain formation and interface states in initial degradation of P3HT:PCBM-based solar cells

22

Swati Arora, Satish Kumar Rajouria, Pankaj Kumar, P K Bhatnagar, Manoj Arora and R P Tandon

Synthesis and characterization of Cu doped cobalt oxide nanocrystals as methane gas sensors

22

Z Sheikhi Mehrabadi, A Ahmadpour, N Shahtahmasebi and M M Bagheri Mohagheghi

Geophysics, astronomy and astrophysics Lorentz-covariant quantum transport and the origin of dark energy

23

Arne Bergstrom

Ionospheric perturbations associated with two recent major earthquakes (M>5.0)

23

S Priyadarshi, S Kumar and A K Singh

Cosmic microwave background radiation in an inhomogeneous spherical space

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R Aurich, P Kramer and S Lustig

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Physica Scripta

Comments section (CAMOP) Dimensions, nodes and phases in quantum numbers

23

A R P Rau

Testing Lorentz symmetry with atoms and light

23

Neil Russell

Optical tomography of Fock state superpositions

24

S N Filippov and V I Man’ko

On multiple adsorptions of hydrogen atoms on graphene

24

Benjamin J Irving, Anthony J H M Meijer and Dean Morgan

Comments section (CCMP) High-temperature superconductivity: the explanation

24

A S Alexandrov

The pairing mechanism of high-temperature superconductivity: experimental constraints

24

Guo-meng Zhao

Comments section (CFRP) Foundations of quantum mechanics?

25

Göran Lindblad

Topical issue (T143) Entanglement dynamics of two independent cavity-embedded quantum dots

25

B Bellomo, G Compagno, R Lo Franco, A Ridolfo and S Savasta

Entanglement dynamics of a bipartite system in squeezed vacuum reservoirs

25

Smail Bougouffa and Awatif Hindi

A smooth, holographically generated ring trap for the investigation of superfluidity in ultracold atoms

25

Graham D Bruce, James Mayoh, Giuseppe Smirne, Lara Torralbo-Campo and Donatella Cassettari

Entanglement in two-mode continuous variable open quantum systems

26

Aurelian Isar

Topical issue (T144) An ECR ion source-based low-energy ion accelerator: development and performance

26

A N Agnihotri, A H Kelkar, S Kasthurirangan, K V Thulasiram, C A Desai, W A Fernandez and L C Tribedi

At the borderline between atomic and nuclear physics: two-body β-decay of highly charged ions

26

Yuri A Litvinov, Fritz Bosch, Christophor Kozhuharov, Xinwen Ma, Thomas Stöhlker, Nicolas Winckler and Takayuki Yamaguchi

Configuration and calibration of a flat field grating spectrometer in the wavelength range 7–60 Å with a Manson ultrasoft x-ray source Y Yang, Z Shi, Z Fei, X Jin, J Xiao, R Hutton and Y Zou

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General

Delay-improved signal propagation in globally coupled bistable systems J H Yang and X B Liu Institute of Vibration Engineering Research, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, People’s Republic of China E-mail: [email protected], [email protected]

Electromagnetic potentials without gauge transformations A Chubykalo1, A Espinoza1 and R Alvarado Flores2 1

nidad Academica de Fisica, Universidad Autonoma de Zacatecas, A.P. C-580, U Zacatecas, Mexico

2

entro de Estudios Multidisciplinarios, Universidad Autónoma de Zacatecas, Av. C Insurgentes 108A, tercer piso, col. Centro, Zacatecas, Zac, C.p. 98000, Mexico

E-mail: [email protected]

2011 Phys. Scr. 84 015009

2011 Phys. Scr. 83 065008 Abstract Based on the mechanism of vibrational resonance, we improve the weak low-frequency signal propagation in globally coupled bistable systems by time delay feedback. In the system chains, the weak low-frequency signal is added only to the first oscillator and the identical high-frequency signals are added to all of the oscillators. Both numerical and analytical results show that the response amplitude of the last oscillator to the low-frequency signal varies periodically with the delay parameter by two different periods, which equal the periods of the two exciting signals, respectively. In addition, the vibrational resonance can also be induced to improve signal propagation by adjusting the coupling strength. Comparing with the delay-free systems, with the cooperation of the high-frequency signal and time delay feedback, the weak low-frequency signal can be transmitted much more efficiently in the delayed systems.

Amplification of weak signals via the nonadiabatic regime of stochastic resonance in a bistable dynamical system with time delay Lu-Chun Du and Dong-Cheng Mei Department of Physics, Yunnan University, Kunming 650091, People’s Republic of China E-mail: [email protected]

2011 Phys. Scr. 84 015003 Abstract The non-adiabatic regime of stochastic resonance (SR) in a bistable system with time delay, an additive white noise and a periodic signal was investigated. The signal power amplification η was employed to characterize the SR of the system. The simulation results indicate that (i) in the case of intermediate frequency Ω of the periodic signal, the typical behavior of SR is lowered monotonically by increasing the delay time τ; in the case of large Ω, τ weakens the SR behavior and then enhances it, with a non-monotonic behavior as a function of time delay; (ii) time delay induces SR when A is above the threshold, whereas no such resonance exists in the absence of time delay; (iii) time delay induces a transition from bimodal to unimodal configuration of η; (iv) varying the particular form of time delay results in different phenomena.

Abstract In this paper, we show that the use of the Helmholtz theorem enables the derivation of uniquely determined electromagnetic potentials without the necessity of using gauge transformation. We show that the electromagnetic field comprises two components, one of which is characterized by instantaneous action at a distance, whereas the other propagates in retarded form with the velocity of light. In our attempt to show the superiority of the new proposed method to the standard one, we argue that the actionat-a-distance components cannot be considered as a drawback of our method, because the recommended procedure for eliminating the action at a distance in the Coulomb gauge leads to theoretical subtleties that allow us to say that the needed gauge transformation is not guaranteed. One of the theoretical consequences of this new definition is that, in addition to the electric E and magnetic B fields, the electromagnetic potentials are real physical quantities. We show that this property of the electromagnetic potentials in quantum mechanics is also a property of the electromagnetic potentials in classical electrodynamics.

Coulomb screening of 2D massive Dirac fermions Jia-Ning Zhang Chern Institute of Mathematics, Nankai University, Tianjin 300071, People’s Republic of China E-mail: [email protected]

2011 Phys. Scr. 83 035002 Abstract A model of 2D massive Dirac fermions, interacting with instantaneous 1/r Coulomb interaction, is presented in order to mimic the physics of gapped graphene. The static polarization function is calculated explicitly to analyze the screening effect at finite temperature and density. The results are compared with the massless case. We also show that various results in other works can be reproduced with our model in a straightforward and unified manner.

Monthly downloads as high as

27 300 during 2011

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Resolution of the Klein paradox A D Alhaidari Saudi Center for Theoretical Physics, Jeddah, Saudi Arabia E-mail: [email protected]

functions. The obtained explicit analytical expressions for the frequency, period and displacement generate results that compare excellently with the numerically computed ones for moderate as well as sufficiently high values of the initial amplitudes. For larger initial amplitudes close to 180° Padé approximants of the found series solutions lead to fairly accurate results whose relative errors as compared with the exact values are less than 1%.

2011 Phys. Scr. 83 025001 Abstract We present a resolution of the Klein paradox within the framework of oneparticle relativistic quantum mechanics. Not only reflection becomes total but the vacuum remains neutral as well. This is accomplished by replacing the physical pair production process with virtual negative energy ‘incidence’ within the barrier in a similar manner to what is done with virtual sources in optics and image charges in electrostatics.

The Schmidt number as a universal entanglement measure J Sperling and W Vogel Arbeitsgruppe Quantenoptik, Institut für Physik, Universität Rostock, D-18051 Rostock, Germany E-mail: [email protected], [email protected], [email protected]

On eigenvalue problems in quantum mechanics Aparna Saha1, Umapada Das2 and B Talukdar1 1

Department of Physics, Visva-Bharati University, Santiniketan 731235, India

2

Department of Physics, Abhedananda College, Sainthia 731234, India


2011 Phys. Scr. 83 065003 Abstract To solve quantum mechanical eigenvalue problems using the algorithmic methods recently derived by Nikiforov and Uvarov (1988 Special Functions of Mathematical Physics (Basel: Birkhäuser)) and Ciftci et al (2003 J. Phys. A: Math. Gen. 36 11807), one needs to first convert the associated wave equation into hypergeometric or closely related forms. We point out that once such forms are obtained, the eigenvalue problem can be satisfactorily solved by only imposing the condition that the regular infinite series solutions of the equations should become polynomials, and one need not take recourse to the use of the algorithmic methods. We first demonstrate the directness and simplicity of our approach by dealing with a few case studies and then present new results for the Woods–Saxon potential.

2011 Phys. Scr. 83 045002 Abstract The class of local invertible operations is defined, and the invariance of entanglement under such operations is established. For the quantification of entanglement, universal entanglement measures are defined, which are invariant under local invertible transformations. They quantify entanglement in a very general sense. It is shown that the Schmidt number is a universal entanglement measure, which is most important for the general amount of entanglement. For special applications, pseudo-measures are defined to quantify the entanglement useful for a certain quantum task. The entanglement quantification is further specified by operational measures, which include the observables accessible by a given experimental setup.

Accurate analytic approximation to the nonlinear pendulum problem M Turkyilmazoglu Mathematics Department, University of Hacettepe, 06532 Beytepe, Ankara, Turkey E-mail: [email protected]

2011 Phys. Scr. 84 015005 Abstract This paper is concerned with the accurate analytic solution of the nonlinear pendulum differential equation. Instead of the traditional Taylor series or asymptotic methods, the homotopy analysis technique is used, which does not require a small perturbation parameter or a large asymptotic parameter. It is shown here that such a method is extremely powerful in gaining the pendulum solution in terms of purely trigonometric cosine

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Physica Scripta

Nuclear physics

Nuclear structure of the neutron-rich 140–148Ba isotopes

Characteristics of multiplicity distribution of target fragments in forward and backward hemispheres in high-energy nucleus–nucleus interactions Dipak Ghosh , Argha Deb and Swarnapratim Bhattacharyya 1

1

A R H Subber and Falih H Al-Khudair Department of Physics, College of Education, Basrah University, Basrah, Iraq E-mail: [email protected]

2011 Phys. Scr. 84 035201

2,3

1

epartment of Physics, Nuclear and Particle Physics Research Centre, Jadavpur D University, Kolkata 700 032, India

2

epartment of Physics, New Alipore College, L Block, New Alipore, Kolkata D 700 053, India

3

Author to whom any correspondence should be addressed


Abstract The level structure of even–even neutron-rich 140–148Ba isotopes was studied in the framework of the interacting boson model. The reduced transition probabilities B(E2) of these nuclei were calculated. A set of parameters was used in the calculation to approach the values with the measured data. It was pointed out that interacting boson approximations are equitably reliable for the description of spectra and other properties. It was found that there is a rapid transition between spherical and rotational shapes.

2011 Phys. Scr. 84 015201 Abstract A detailed study on the mechanism of the evaporation of target fragments in the forward and backward hemispheres in 12C–AgBr interactions at 4.5A GeV, 28Si–AgBr interactions at 14.5A GeV, 16O–AgBr interactions at 60A GeV and 32S–AgBr interactions at 200A GeV is carried out in terms of the multiplicity distribution. The nature of the multiplicity distribution in the forward and backward hemispheres is found to be different across all the interactions. The asymmetry parameters and the forward–backward ratios were also calculated for the above-mentioned interactions. The asymmetry parameters and the forward–backward ratios from other nucleus–nucleus interaction data were compared with our results. The forward–backward ratios of target fragments are found to be nearly the same for all the nucleus–nucleus interactions. The forward–backward ratios of all the interactions are greater than 1, suggesting that the probability of emission of fragments in the forward hemisphere is higher than that in the backward direction. The multiplicity moment, entropy and reduced entropy, i.e. the ratio of entropy to average multiplicity of target fragments, are evaluated in both the forward and backward hemispheres for all the four abovementioned interactions. The values of multiplicity moments are found to be energy independent up to 60A GeV energy in the backward hemisphere. The reduced entropy is also found to be almost energy independent to within experimental error in the backward hemisphere. No such observation can be made in the forward hemisphere. The total entropy of the target fragments is found to be higher in the forward hemisphere. A study of correlation in terms of the scaled variance was also carried out in both the hemispheres for all the nucleus–nucleus interactions. No systematic variation of correlation either with energy or with the size of the projectile nucleus has been noticed. The study yields quite interesting information on the mechanism of particle evaporation in the backward hemisphere.

Atomic and molecular physics

The mechanical, electronic structure and thermodynamic properties of B2-based AgRE studied from first-principles Xiaoma Tao1, Hongmei Chen1, Xingxiu Li1, Yifang Ouyang1,2 and Shuzhi Liao2 1

K ey Laboratory of New Processing Technology for Nonferrous Metals and Materials of the Ministry of Education, Department of Physics, Guangxi University, Nanning 530004, People’s Republic of China

2

K ey Laboratory of Low Dimensional Quantum Structures and Quantum Control of the Ministry of Education, Department of Physics, Hunan Normal University, Changsha 410081, People’s Republic of China


2011 Phys. Scr. 83 045301 Abstract The lattice constants, formation enthalpies, bulk modulus, elastic constants and electronic structures of B2-based AgRE (RE=Sc, Y and La–Lu) have been calculated by means of first-principles based on the density functional theory. The shear modulus, Young’s modulus and Poisson’s ratio have been estimated from the calculated elastic constants. The electronic structures were calculated to give insight into the bonding mechanism in AgRE compounds. In addition, the Debye temperature, heat capacity, thermal expansion and Grüneisen parameter of AgRE compounds were obtained by applying the Debye model. The calculated lattice constants, formation enthalpies and elastic constants are all in good agreement with the available experimental data and other theoretical results. The formation enthalpy of B2-AgRE varies linearly with the density of states at the Fermi level.

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Electromagnetism, optics, acoustics, heat transfer, classical mechanics and fluid dynamics

U-shaped multi-band negative-index bulk metamaterials with low loss at visible frequencies Kun Song, Quanhong Fu and Xiaopeng Zhao Department of Applied Physics, Northwestern Polytechnical University, Xi’an 710129, People’s Republic of China E-mail: [email protected]

2011 Phys. Scr. 84 035402 Abstract We study bulk negative-index metamaterials made up of U-shaped cells at visible frequencies that can realize multi-band negative refractive index with very low loss based on high-order resonance. The mechanism of multi-band negative refractive index can be interpreted by analyzing the transmission modes, current distribution, effective LC circuit models and kinetic energy of electrons. In the low-frequency region, the multi-band resonances are mainly due to the cell itself; in the high-frequency region, they are mainly due to the interaction between adjacent cells. Compared with cut-wire pairs, U-shaped cells can realize resonances more easily at high frequencies and produce more negative-index transmission bands.

Optimization of the bubble radius in a moving single bubble sonoluminescence Mona Mirheydari1,2, Rasoul Sadighi-Bonabi1, Nastaran Rezaee1,2 and Homa Ebrahimi1 1

Department of Physics, Sharif University of Technology, 11365-91, Tehran, Iran

2

epartment of Physics, Islamic Azad University, Central Tehran Branch, D 14676-86831, Tehran, Iran


2011 Phys. Scr. 83 055403 Abstract A complete study of the hydrodynamic force on a moving single bubble sonoluminescence in N-methylformamide is presented in this work. All forces exerted, trajectory, interior temperature and gas pressure are discussed. The maximum values of the calculated components of the hydrodynamic force for three different radii at the same driving pressure were compared, while the optimum bubble radius was determined. The maximum value of the buoyancy force appears at the start of bubble collapse, earlier than the other forces whose maximum values appear at the moment of bubble collapse. We verified that for radii larger than the optimum radius, the temperature peak value decreases.

Mixed convection boundary-layer flow about an isothermal solid sphere in a nanofluid L Tham1, R Nazar2 and I Pop3

Propagation of shock waves in a viscous medium Harish C Yadav and R K Anand

1

F aculty of Agro Industry and Natural Resources, Universiti Malaysia Kelantan, Kelantan, Malaysia

2

chool of Mathematical Sciences, Faculty of Science and Technology, Universiti S Kebangsaan Malaysia, Selangor, Malaysia

3

Faculty of Mathematics, University of Cluj, Cluj, Romania

Department of Physics, University of Allahabad, Allahabad-211002, India


E-mail: [email protected], [email protected]

2011 Phys. Scr. 84 025403

2011 Phys. Scr. 83 065402 Abstract A theoretical model for entropy production in a viscous medium due to the propagation of shock waves has been developed. An exact general solution is achieved for plane, cylindrical and spherical symmetries of shock waves in viscous flow, which on numerical substitutions gives variations in the entropy production, temperature ratio and particle velocity in the shock transition region with the coefficient of viscosity, specific heat ratio, shock strength, initial density and initial pressure.

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Abstract The steady mixed convection boundary-layer flow of a nanofluid about a solid sphere with constant surface temperature has been studied for cases of both assisting and opposing flows. The resulting system of nonlinear partial differential equations is solved numerically using an implicit finitedifference scheme known as the Keller-box method. The solutions for the flow and heat-transfer characteristics are evaluated numerically for various values of the parameters, namely the nanoparticle volume fraction { and the mixed convection parameter λ at Prandtl numbers Pr=0.7 and 6.2. The three different types of nanoparticles considered are Al2O3, Cu and TiO2, using water-based fluid with Pr=6.2. It is found that for each particular nanoparticle, as the nanoparticle volume fraction { increases, the skin friction coefficient and the heat-transfer rate at the surface also increase. This leads to an increase in the value of the mixed convection parameter λ, which at first gives no separation.

Physica Scripta

Generation of continuous-variable entanglement in a three-level system coupled with a parametric oscillator Yong-Hong Ma School of Mathematics, Physics and Biological Engineering, Inner Mongolia University of Science and Technology, Baotou 014010, People’s Republic of China E-mail: [email protected]

2011 Phys. Scr. 83 025403 Abstract We consider a nondegenerate three-level cascade laser driven by a classical field with a parametric oscillator. The dynamic evolution of the master equation is investigated and the steady-state entanglement between two modes is investigated. We show that introducing the parametric oscillator can enhance the entanglement between the two-mode cavity. In particular, with the help of the classical field, a high intensity of entangled light between the two modes can be achieved.

Power-flow formulation of a ray approach to the modelling of inhomogeneous waves M Tereshchenko1,4, F Castejón1,3, S Pavlov2 and A Cappa3 1

Instituto de Biocomputación y Física de Sistemas Complejos, 50018 Zaragoza, Spain

2

Institute of Plasma Physics, KhIPT, 61108 Kharkov, Ukraine

3

Laboratorio Nacional de Fusión, EURATOM-CIEMAT, 28040 Madrid, Spain

4

Prokhorov Institute of General Physics, 119991 Moscow, Russia


2011 Phys. Scr. 84 025401 Abstract In this paper, we elaborate on quite a simple analytical framework for the physically intelligible principle of a ray description of inhomogeneous wavefields on the basis of the generic properties of active and reactive wave power flows. While being very close to traditional geometric optics (GO) in the limit of lossless media, in substantially non-Hermitian systems this approach turns out to be a distinct method capable of keeping up ray trajectories in a real-valued domain. We also demonstrate that the ray method based on power-flow analysis is mostly free from the standard limitations of GO. In this regard, the proper use of the ray-tracing technique can be justified for modelling a wide range of non-regular wave phenomena if wave power transport is under consideration. The paraxial equations are shown to comply with the power-flow formulation, thus finding an extended range of applicability.

Physics of gases, plasmas and electrical discharges

Nonplanar ion-acoustic solitary waves in electron–positron–ion plasmas with electrons following a q-nonextensive distribution P Eslami1, M Mottaghizadeh2 and Hamid Reza Pakzad3,4 1

Department of Physics, Ferdowsi University, Mashhad, Iran

2

Department of Physics, Mashhad Branch, Islamic Azad University, Mashhad, Iran

3

Department of Physics, Bojnourd Branch, Islamic Azad University, Bojnourd, Iran

4

Author to whom any correspondence should be addressed


2011 Phys. Scr. 83 065502 Abstract Cylindrical and spherical Korteweg–de Vries equations were derived for ionacoustic solitary waves in an unmagnetized three species plasma system comprised of cold ions, nonextensive electrons and thermal positrons by using standard reductive perturbation methods. The effects of nonplanar geometry and q-nonextensive electrons on the profiles of the amplitudes and widths of solitary structures were examined numerically.

The 3+1 dimensional Kadomtsev– Petviashvili Burgers’ equation in non-uniform dusty plasmas Li-Ping Zhang1, Ju-Kui Xue2 and Li-Hua Yuan1 1

chool of Sciences, LanZhou University of Technology, Lanzhou 730050, People’s S Republic of China

2

ollege of Physics and Electronic Engineering, Northwest Normal University, C Lanzhou 730070, People’s Republic of China


2011 Phys. Scr. 83 045501 Abstract Using the perturbation method, the 3+1 dimensional modified variable coefficient Kadomtsev–Petviashvili (MKP) Burgers’ equation governing nonlinear dust acoustic shock waves is derived with the combined effects of non-adiabatic dust charge fluctuation, higher-order transverse perturbation and the non-thermally distributed ions in inhomogeneous dusty plasmas due to spatial gradients of dust charge and plasma densities for the first time. The MKP Burgers’ equation is reduced to the standard variable coefficient Kadomtsev–Petviashvili (KP) Burgers’ equation. A particular solution of this KP Burgers’ equation is also obtained. It is shown that the dust acoustic shock waves can exist in the KP Burgers’ equation.

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Experimental and theoretical studies of the direct-current breakdown voltage in argon at micrometer separations

Dust acoustic instability with Lorentzian kappa distribution

M Klas1, Š Matejcˇík1, B Radjenovic´2 and M Radmilovic´-Radjenovic´2

Department of Physics, Nanchang University, Nanchang 330047, People’s Republic of China

1

epartment of Experimental Physics, Comenius University, Mlynská dolina F2, D 84248 Bratislava, Slovakia

2

Institute of Physics, University of Belgrade, Pregrevica 118, 11080 Belgrade, Serbia

Sanqiu Liu and Jing Li


2011 Phys. Scr. 84 035504


2011 Phys. Scr. 83 045503 Abstract In this paper, the dc breakdown in argon has been measured in the discharge system consisting of two parallel planar Cu electrodes at separations from 20 to 500 μm varying the pressure from 4.5 to 690 torr. The measured breakdown voltage curves were systematically analyzed and a corresponding scaling law was suggested. The estimation of the secondary emission coefficient γ as a function of the reduced electric field was based on experimental data and simple theoretical studies. Additionally, particlein-cell/Monte Carlo collision simulations were performed to understand in more detail the processes involved in the dc discharge breakdown. Good agreement was found between experimental and simulation results.

Abstract The instability of dust acoustic waves (DAWs) driven by ions and electrons with different drift velocities in an unmagnetized, collisionless, isotropic dusty plasma was investigated based on kinetic theory. The electrons, ions and dust particles are all modeled by using the generalized Lorentzian kappa distributions. It is found that the instability growth rate depends not only on the mass, temperature, density ratios of the components and ion–electron drift velocity ratio, but also on the spectral index for each component. The effects of the indices on the instability growth rate of DAWs have been discussed in detail.

Instabilities in strongly coupled ultracold neutral plasmas

Electron acoustic solitary waves with kappa-distributed electrons

M Rosenberg1 and P K Shukla2 1

epartment of Electrical and Computer Engineering, University of California, D San Diego, La Jolla, CA 92930, USA

S Devanandhan1, S V Singh1,2 and G S Lakhina1

2

UB International Chair, International Centre for Advanced Studies in Physical R Sciences, Faculty of Physics and Astronomy, Ruhr University Bochum, 44780 Bochum, Germany

1

Indian Institute of Geomagnetism, New Panvel (West), Navi Mumbai, India

2

School of Physics, University of Kwazulu-Natal, Durban, South Africa



2011 Phys. Scr. 83 015503

2011 Phys. Scr. 84 025507 Abstract Electron acoustic solitary waves are studied in a three-component, unmagnetized plasma composed of hot electrons, fluid cold electrons and ions having finite temperatures. Hot electrons are assumed to have kappa distribution. The Sagdeev pseudo-potential technique is used to study the arbitrary amplitude electron-acoustic solitary waves. It is found that inclusion of cold electron temperature shrinks the existence regime of the solitons, and soliton electric field amplitude decreases with an increase in cold electron temperature. A decrease in spectral index, κ, i.e. an increase in the superthermal component of hot electrons, leads to a decrease in soliton electric field amplitude as well as the soliton velocity range. The soliton solutions do not exist beyond Tc/Th>0.13 for κ=3.0 and Mach number M=0.9 for the dayside auroral region parameters.

Abstract In ultracold neutral plasmas the ions are strongly coupled in the liquid phase, while the electrons are weakly coupled. The effect of strong ion correlations on the dispersion relation of possible ion-beam plasma instabilities is considered.

Influence of gas pressure on the structure and dynamics of dust rotation in magnetized dusty plasmas F Huang1, Y H Liu2, M F Ye2 and L Wang2 1

ollege of Science, China Agricultural University, Beijing 100083, People’s C Republic of China

2

Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China


2011 Phys. Scr. 83 025502 Abstract The structure and dynamics of dust rotation under a magnetic field at different gas pressures in the sheath of a radio-frequency discharge are

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Physica Scripta

investigated in this paper. The influence of gas pressure on the rotational properties of the dust particles located in different layers is studied in detail. Both rigid rotation (all the dust particles move with a constant angular velocity) and sheared rotation (the angular velocity of the dust particles has a radial distribution) of the dust particles induced by a magnetic field are observed. With increasing gas pressure, the angular velocity of the rotating dust particles in all layers decreases. Under specific experimental conditions, the angular velocity of the dust particles in the lower layer is lower than that of the dust particles in the upper layers. With increasing gas pressure, dust particles in the lower layer stop rotating earlier than those in the upper layers. At a critical (high) gas pressure, dust particles in the lower layers also reverse their rotation direction earlier than those in the upper layers. Within the same dust layer, particles located in the inner region stop rotating and reverse their rotation direction earlier than those in the outer region. At a sufficiently high angular velocity, a void (dust-free region) is formed in the dust cloud, leaving the dust particles rotating in a layer at the system edge. When the gas pressure becomes too high, the voids can be destroyed, and the dust particles are redistributed in the dust cloud. Finally, a 3D spindle-shaped configuration of the dust cloud in the plasma sheath can also be obtained. The experimental results are discussed in detail.

Condensed matter: structural, mechanical and thermal properties

Electrical properties of the double perovskite oxide Ho2CuZrO6 D K Mahato1, Alo Dutta2, Nishant Kumar3 and T P Sinha2 1

Department of Physics, National Institute of Technology, Patna 800 005, India

2

epartment of Physics, Bose Institute, 93/1, Acharya Prafulla Chandra Road, D Kolkata 700 009, India

3

Department of Physics, T M Bhagalpur University, Bhagalpur 812007, India


2011 Phys. Scr. 84 015602 Abstract The double perovskite oxide holmium copper zirconate, Ho2CuZrO6 (HCZ), was synthesized by a solid-state reaction technique. The crystal structure of HCZ shows a monoclinic phase. The dielectric relaxation of HCZ was investigated in the frequency range 44 Hz–1 MHz and in the temperature range 40–360 °C by using impedance spectroscopy. The complex impedance data were analysed by the Cole–Cole model. The ac conductivity follows the power law. The value of activation energy obtained from the temperature dependence of the dc conductivity plot indicates a hopping-type conduction mechanism. The scaling behaviour of the imaginary part of impedance indicates that relaxation in HCZ describes the same mechanism at various temperatures.

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The effect of heating conditions on the properties of nano- and microstructured Ni–Zn ferrite A Sutka1, K A Gross2, G Mezinskis1, G Bebris3 and M Knite4 1

Institute of Silicate Materials, Riga Technical University, Azenes 14/24, LV-1048, Latvia

2

Department of Materials Engineering, Monash University, VIC 3168, Australia

3

State Forensic Science Bureau, Hospitalu 55, LV-1013, Latvia

4

Institute of Technical Physics, Riga Technical University, Azenes 14/24, LV-1048, Latvia


2011 Phys. Scr. 83 025601 Abstract The structural, microstructural and morphological, as well as electric and dielectric, properties of nickel–zinc ferrite (Ni0.3Zn0.7Fe2O4) derived from sol–gel auto-combustion have been studied after sintering from 900 to 1300 °C. The effect of heating rate has not been previously investigated and is reported here. X-ray diffraction showed a pure cubic spinel after calcination. Atomic force microscopy revealed nanosized particles after calcination, but scanning electron microscopy showed nanosized grains after sintering at 900 °C. The heating rate has a marked effect on oxidation of Fe3+ to Fe2+, showing an additional approach to control charge carrier concentration in Ni–Zn ferrites (powder and monoliths). The heating rate also influences the average particle size and distribution. Grain size and resistivity of sintered pellets do not show significant change with heating rate, proving that resistivity is mainly dictated by the number of grain boundaries. The dielectric loss tangent curves at room temperature exhibit dielectric relaxation peaks attributed to the similarity in frequency of charge hopping between the localized charge states and external fields. The relaxation peak shifts to higher frequencies for ferrites with nanosized grains.

Structural and dielectric properties of Cr-doped Ni–Zn nanoferrites S Nasir, M Anis-ur-Rehman and Muhammad Ali Malik Applied Thermal Physics Laboratory, Department of Physics, COMSATS Institute of Information Technology, Islamabad 44000, Pakistan E-mail: [email protected]

2011 Phys. Scr. 83 025602 Abstract Cr-doped Ni–Zn ferrite nanoparticles having the general formula Ni0.5Zn0.5CrxFe2−xO4 (x=0.1, 0.3, 0.5) were prepared by the simplified sol–gel method. The structural and dielectric properties of the samples sintered at 750±5 °C were studied. X-ray diffraction (XRD) patterns confirm the single-phase spinel structure of the prepared samples. The crystallite size calculated from the most intense peak (3 1 1) using the Debye–Scherrer formula was 29–34 nm. Scanning electron microscope images showed that the particle size of the samples lies in the nanometer regime. The dielectric constant (εr), dielectric loss tangent (tan δ) and ac electrical conductivity (σac) of nanocrystalline Cr–Ni–Zn ferrites were investigated as a function of frequency and Cr concentration. The dependence of εr, tan δ and σac on the frequency of alternating applied electric field is in accordance with the Maxwell–Wagner model. The effect of Cr doping on the dielectric and electric properties was explained on the basis of cations distribution in the crystal structure.

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Structural, electrical and magnetic studies of nickel–zinc nanoferrites prepared by simplified sol–gel and co-precipitation methods S Nasir and M Anis-ur-Rehman Applied Thermal Physics Laboratory, Department of Physics, COMSATS Institute of Information Technology, Islamabad 44000, Pakistan E-mail: [email protected]

2011 Phys. Scr. 84 025603 Abstract Ferrite nanoparticles, particularly nickel–zinc ferrite nanoparticles, are novel materials for high-frequency applications. Nanoparticles with a composition of Ni0.5Zn0.5Fe2O4 were prepared by two different processes, namely the co-precipitation and simplified sol–gel methods. Powder x-ray diffraction (XRD) patterns confirmed the single-phase spinel structure for the as-prepared samples. Samples were sintered at 555 and 755 °C, after which the structural, electrical and magnetic properties were studied. The crystallite sizes, as determined from XRD data, increased with sintering temperature. The dc electrical resistivity measurements were performed as a function of temperature, with the two-probe method in the temperature range from room temperature to 450 °C. The activation energy and drift mobility were calculated from the temperature-dependent dc electrical resistivity measurements. The dielectric constant and dielectric loss tangent for all the samples were determined as a function of frequency, and the frequency range used was from 20 Hz to 3 MHz at room temperature. The samples prepared using the simplified sol–gel method have lower dielectric constant values compared to those of the samples prepared using the co-precipitation method, and those prepared by the former method are more suitable for high-frequency applications. For the magnetic properties, a vibrating sample magnetometer was used. Saturation magnetization and coercivity increased with an increase in sintering temperature.

Pseudopotential calculation of the bulk modulus and phonon dispersion of the bcc and hcp structures of titanium Mahmoud Jafari1, Niloofar Zarifi1, Maryam Nobakhti1, Atefeh Jahandoost1 and Maryam Lame2 1

P hysics Department, KN Toosi University of Technology, PO Box 16315-1618, Tehran, Iran

2

Shahid Rajaee University, Tehran, Iran


2011 Phys. Scr. 83 065603 Abstract The structural stability of Ti in the hexagonal-closed-packed and bodycentered cubic structures was studied by means of the full potential linearized augmented plane wave method. The effect of pressure on the bulk modulus of the crystal structures was investigated. In this study, the plane wave ultrasoft pseudopotential method was used to calculate the elastic constants, bulk modulus and phonon frequency of Ti. Phonon calculations were performed by employing the density functional perturbation theory in real space, using the calculated lattice dynamical force constants. All calculations were based on the density functional theory with the generalized gradient approximation and local density approximation, which well describe the properties of the above-mentioned metal.

Effect of substrate temperature in the synthesis of BN nanostructures M Sajjad, H X Zhang, X Y Peng and P X Feng Department of Physics, University of Puerto Rico, PO Box 23343, San Juan 00931, Puerto Rico E-mail: [email protected]

Negative differential conductivity in bilayer graphene controlled by an external voltage and in the presence of a magnetic field N N Yanyushkina1, M B Belonenko2 and N G Lebedev1 1

Volgograd State University, Volgograd, Russia

2

Volgograd Institute of Business, Laboratory of Nanotechnologies, Volgograd, Russia


2011 Phys. Scr. 83 015603 Abstract The current–voltage characteristic of graphene bilayers was obtained in the case of strong electric and magnetic fields. Regions of negative differential conductivity were obtained when the magnetic field was perpendicular to the layers of the bilayer graphene. In addition, the possibility of generating terahertz pulses was discovered in such systems for a sufficiently wide range of interlayer voltage.

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2011 Phys. Scr. 83 065601 Abstract Boron nitride (BN) nanostructures were grown on molybdenum discs at different substrate temperatures using the short-pulse laser plasma deposition technique. Large numbers of randomly oriented nanorods of fiber-like structures were obtained. The variation in the length and diameter of the nanorods as a function of the substrate temperature was systematically studied. The surface morphologies of the samples were studied using scanning electron microscopy. Energy dispersive x-ray spectroscopy confirmed that both the elements boron and nitrogen are dominant in the nanostructure. The x-ray diffraction (XRD) technique was used to analyse BN phases. The XRD peak that appeared at 26° showed the presence of hexagonal BN phase, whereas the peak at 44° was related to cubic BN content in the samples. Raman spectroscopic analysis showed vibrational modes of sp2- and sp3-type bonding in the sample. The Raman spectra agreed well with XRD results.

Physica Scripta

The fabrication, characterization and electrochemical corrosion behavior of Zn-TiO2 composite coatings M K Punith Kumar1, T V Venkatesha1, M K Pavithra1 and A Nithyananda Shetty2 1

epartment of PG Studies and Research in Chemistry, Kuvempu University, D Shankaraghatta 577 451, India

2

epartment of Chemistry, National Institute of Technology Karnataka, Surathkal D 575 025, India


2011 Phys. Scr. 84 035601 Abstract Metal-nanoparticle composite coatings improve the hardness, wear resistance and corrosion resistance properties of metal coatings. In this work, TiO2 nanoparticles were chosen as second-phase particles to generate anticorrosive Zn composite coatings. The TiO2 nanoparticles were dispersed in a Zn plating solution to co-deposit them with Zn. The Zn-TiO2 composite coatings were then characterized by scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDS) and x-ray diffraction methods. The presence of TiO2 particles in the composite was confirmed by SEM images and EDS spectra. The Zn-TiO2 composite coatings incorporated with different amounts of TiO2 particles were tested for corrosion performance by polarization and electrochemical impedance spectroscopy, and the dissolution behavior of the coatings that had been immersed in corrosive media for a long time was studied. Improved corrosion resistance properties of the Zn-TiO2 composite coatings were confirmed by polarization studies, fitted Nyquist plots, an increase in phase angle and a shift in the Rct characteristic peak of the Bode plot.

Physical and chemical properties of a Ga-doped ZnO crystal Arvids Stashans1, Katia Olivos1,2 and Richard Rivera1 1

rupo de Fisicoquímica de Materiales, Universidad Técnica Particular de Loja, G Apartado 11-01-608, Loja, Ecuador

2

E scuela de Geología y Minas, Universidad Técnica Particular de Loja, Apartado 11-01-608, Loja, Ecuador


2011 Phys. Scr. 83 065604 Abstract First-principles calculations based on density functional theory and strengthened by Hartree–Fock computations have been performed to study a Ga-doped wurtzite-type ZnO crystal. The large 108-atom supercell used throughout this work allows one to model a single point defect within the periodic supercell model. Thus, the Ga impurity produced purely local effects on the properties of the material. The electronic band structure was obtained for both pure and impurity-doped materials. The occurrence of free electrons in the conduction band was observed after the incorporation of Ga, implying the Ga dopant’s contribution to n-type electrical conductivity in the ZnO crystal, in agreement with known experimental data. An analysis of the charges on atoms and obtained atomic displacements in the region surrounding the defect showed that there is some alteration in the chemical bonding because of the presence of Ga atoms. In particular, the ionic bonding is strengthened in the defect’s neighbourhood.

Condensed matter: electronic structure, electrical, magnetic and optical properties

The structural, elastic and vibrational properties of the DyX (X=P, As) compounds H Özıs¸ık1, Y Ö Çiftci2, K Çolakogˇlu2 and E Deligöz1 1

Department of Physics, Aksaray University, 68100 Aksaray, Turkey

2

Department of Physics, Gazi University, Teknikokullar, 06500 Ankara, Turkey


2011 Phys. Scr. 83 035601 Abstract A detailed theoretical study of the structural, elastic and vibrational properties of DyX (X=P, As) compounds is presented in this paper by performing ab initio calculations based on density functional theory using the VASP code. For describing the interaction between electrons and ions, the projector-augmented wave method is used. The generalizedgradient approximation is chosen for the exchange-correlation functional. The calculated structural parameters, such as the lattice constant, bulk modulus and second-order elastic constants, are presented. The highpressure phase of both compounds is investigated and the phase transition pressure from NaCl (B1) to high-pressure phase (B2) is determined. To gain further information, we have calculated the Zener anisotropy factor (A), Poisson’s ratio (ν), Young’s modulus (E), shear modulus (C'), elastic wave velocities, Debye temperature, phonon frequencies and one-phonon density of states for the B1 structure of these compounds. The temperaturedependent variations of some thermodynamic properties such as entropy, heat capacity, internal energy and free energy are also predicted for the same compounds in the B1 phase.

A carbon nanotube-based pressure sensor Kh S Karimov1,2, M Saleem1,3, Z M Karieva4, Adam Khan1, T A Qasuria1 and A Mateen1 1

IK Institute of Engineering Sciences and Technology, Topi 23640, District Swabi, G Pakistan

2

P hysical Technical Institute of Academy of Sciences, Rudaki Avenue 33, Dushanbe 734025, Tajikistan

3

Government College Township, Lahore 54770, Pakistan

4

Tajik Technical University, Rajabov Street 10, Dushanbe 734000, Tajikistan


2011 Phys. Scr. 83 065703 Abstract In this study, a carbon nanotube (CNT)-based Al/CNT/Al pressure sensor was designed, fabricated and investigated. The sensor was fabricated by depositing CNTs on an adhesive elastic polymer tape and placing this in an elastic casing. The diameter of multiwalled nanotubes varied between 10 and 30 nm. The nominal thickness of the CNT layers in the sensors was in the range ~300–430 μm. The inter-electrode distance (length) and the width of the surface-type sensors were in the ranges 4–6 and 3–4 mm, respectively. The dc resistance of the sensors decreased 3–4 times as the pressure was increased up to 17 kN m−2. The resistance–pressure relationships were simulated.

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Specific heat and magnetization studies of RMnO3 (R=Sm, Eu, Gd, Tb and Dy) multiferroics N Pavan Kumar, G Lalitha and P Venugopal Reddy Department of Physics, Osmania University, Hyderabad 500007, India E-mail: [email protected]

2011 Phys. Scr. 83 045701 Abstract A series of multiferroic materials with the compositional formula RMnO3 (where R=Sm, Eu, Gd, Tb and Dy) were prepared by the well-known citrate gel technique. After characterizing the samples structurally, a systematic investigation of specific heat and magnetization studies were performed over the temperature range 4–300 K with different magnetic fields. Based on these studies, it was found that all the samples exhibit a transition in the temperature region 39–54 K and the transition is attributed to ordering of Mn3+ ions (TNMn ). Further, the samples GdMnO3, TbMnO3 and DyMnO3 were found to exhibit another transition (Tlock) in the temperature range 20–29 K. Finally, yet another transition was exhibited by all the samples and it is attributed to the antiferromagnetic (AF) ordering of rare-earth ion moments (TNR ). The entropy at the AF transition TNMn was computed. Finally, using the specific heat data, the Debye temperature values were also calculated. 3+

3+

3+

The photoluminescence and magnetism of nitrogen-implanted ZnO

First-principles study of structural, elastic, electronic, lattice dynamic and optical properties of XN (X=Ga, Al and B) compounds under pressure M Fatmi1, B Ghebouli2, M A Ghebouli3 and Z K Hieba4 1

Research Unit on Emerging Materials, University Ferhat Abbas of Setif, 19000, Algeria

2

Department of Physics, University Ferhat Abbas of Setif, 19000, Algeria

3

Department of Physics, Universitary Center of Bordj Bou-Arreridj, 34000, Algeria

4

Department of Physics, Faculty of Science, Taif University, Ta’if, Saudi Arabia


2011 Phys. Scr. 83 065702 Abstract We have applied the pseudo-potential plane wave method to study the structural, elastic, electronic, lattice dynamic and optical properties of GaN and AlN in the wurtzite lattice and BN with zinc-blende structure. We have found that all elastic constants depend strongly on hydrostatic pressure, except for C44 in wurtzite AlN and GaN that shows a weaker dependence. AlN and GaN present a direct band gap Γ–Γ, whereas BN has an indirect band gap Γ–X. The indirect Γ–K band gap in AlN occurs at about 35 GPa. The top of the valence bands reflects the p electronic character for all structures. There is a gap between optical and acoustic modes only for wurtzite phases AlN and GaN. All peaks in the imaginary part of the dielectric function for the wurtzite lattice GaN and AlN move towards lower energies, while those in the zinc-blende BN structure shift towards higher energies with increasing pressure. The decrease of the static dielectric constant and static refractive index in zinc-blende BN is weaker and it can be explained by its higher elastic constants.

CM Liu1, X Xiang1, Y Zhang2, HQ Gu1, Y Jiang1, M Chen1 and XT Zu1 1

epartment of Applied Physics, University of Electronic Science and Technology of D China, Chengdu 610054, People’s Republic of China

2

School of Physics, Peking University, Beijing 100871, People’s Republic of China


2011 Phys. Scr. 83 045704 Abstract Single crystal ZnO was implanted using nitrogen ions with an energy of 60 keV. The microstructure, photoluminescence (PL) and magnetism were studied in detail. Except for nitrogen, no other impurity can be detected by x-ray photoelectron spectra measurements. The room temperature PL of pure ZnO consists of a weak ultraviolet (UV) emission band and a strong green emission band. The PL and electrical conductivity can be suppressed by nitrogen implantation or by annealing in air. However, the two emission bands of pure ZnO can be enhanced intensively by Ar+ etching. The PL is related to the structure defects. Moreover, the intensity of UV luminescence is likely correlated to the electrical conductivity. Ferromagnetism cannot be obtained in the nitrogen-implanted sample from 77 to 300 K. The absence of ferromagnetism in nitrogen-implanted ZnO may be because there is no strong interaction between N 2p and O 2p electrons as nitrogen is a deep acceptor in ZnO.

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Electric field effects on the intersubband optical absorptions and refractive index in double-electron quantum dots Liangliang Lu and Wenfang Xie Department of Physics, College of Physics and Electronic Engineering, Guangzhou University, Guangzhou 510006, People’s Republic of China E-mail: [email protected]

2011 Phys. Scr. 84 025703 Abstract The linear and nonlinear optical properties such as optical absorption and refractive index change associated with intersubband transitions in a two-electron quantum dot (QD) in the presence of an external electric field have been investigated theoretically by using the perturbation method. The exchange force, which is a strictly quantum mechanical phenomenon, has also been considered. Numerical results on typical GaAs/AlGaAs materials show that an increase of the electric field decreases the oscillator strengths, the peak positions of absorption coefficients as well as the refractive index changes. Additionally, an increase of the confinement frequency (dot size) increases (decreases) the absorption coefficients but does not significantly affect the refractive index changes. It is also observed that the intensity of the illumination and the relaxation time have drastic effects on nonlinear optical properties. Finally, we note that the optical absorption coefficients and refractive index changes of two electrons are about five times higher than that of a one-electron QD.

Physica Scripta

Nonlinear transport through ultra-narrow zigzag graphene nanoribbons: non-equilibrium charge and bond currents

observed to be highly linear even at low fields near the metal–insulator transition temperature. However, the dependence of these promising properties on the nanocrystal size remains to be explored.

Hosein Cheraghchi School of Physics, Damghan University, PO Box 6715-364, Damghan, Iran E-mail: [email protected]

2011 Phys. Scr. 84 015702 Abstract The electronic nonlinear transport through ultra-narrow graphene nanoribbons (sub-10 nm) was studied. A stable region of negative differential resistance (NDR) appears in the I–V characteristic curve of odd zigzag graphene nanoribbons (ZGNRs) at both positive and negative polarity. This NDR originates from a transport gap induced by a selection rule that blocks the electron transition between disconnected energy bands of ZGNR. Based on this transition rule, the on/off ratio of the current increases exponentially with ribbon length up to 105. In addition, charging effects and the spatial distribution of bond currents were studied by using the non-equilibrium Green’s function formalism in the presence of electron–electron interaction at a mean-field level. We also performed an ab initio density functional theory calculation of the transmission through a passivated graphene nanoribbon to demonstrate the robustness of the transport gap against hydrogen termination of the zigzag edges.

Magnetic and transport properties of chemical solution deposited (100)-textured La0.7Sr0.3MnO3 and La0.7Ca0.3MnO3 nanocrystalline thin films

Improvement in the luminous efficiency of MEH-PPV based light emitting diodes using zinc oxide nanorods grown by the electrochemical deposition technique on ITO substrates Rohini B Gupta1, Jitender Kumar1, Devinder Madhwal1, Inderpreet Singh1, I Kaur2, L M Bhardwaj2, S Nagpal1, P K Bhatnagar1 and P C Mathur1 1

aterial Science Laboratory, Department of Electronic Science, University of Delhi M South Campus, New Delhi, India

2

Central Scientific Instruments Organization, Sector-30, Chandigarh, India


2011 Phys. Scr. 84 015705 Abstract Zinc oxide (ZnO) nanorods grown by the electrochemical technique have been used to enhance the luminance of poly[2-methoxy-5-(2’-ethylhexoxy)1,4-phenylenevinylene] (MEH-PPV)-based polymer light-emitting diodes. The luminance of the device with ZnO nanorods is found to increase by more than two times as compared with the device without ZnO nanorods. The diameter of the nanorods used in device fabrication was ~145 nm. The size of the nanorods was estimated from field emission scanning electron microscope images. Optical and structural characterizations of the nanorods were also performed by using absorption, photoluminescence and x-ray diffraction, confirming the formation of ZnO nanorods.

Giray Kartopu1,2, Orhan Yalçin2 and A Serdar Demiray3 Institute for Materials and Surface Technology, University of Applied Sciences Kiel, Grenzstrasse 3, 24149 Kiel, Germany 2 Department of Physics, Faculty of Science, Nigˇde University, 51240 Nigˇde, Turkey

1

3

Department of Physics, Gebze Institute of Technology, 41400 Gebze, Kocaeli, Turkey


2011 Phys. Scr. 84 015702 Abstract A study of the magnetic and electrical properties of (100)-oriented La0.7(Sr,Ca)0.3MnO3 thin films prepared by an optimized chemical solution deposition process on a (100) SrTiO3 single-crystal substrate is reported in this paper. The films were studied by high-resolution scanning electron microscopy, x-ray diffraction, vibrating sample magnetometer, ferromagnetic resonance and four-point-probe electrical measurements. A characteristic nanocrystalline texture with ~15 nm crystallites is observed in both films. Remarkably, the resistivities of these films are three orders of magnitude smaller compared with unoptimized films grown even on the same substrate. The magnetotransport properties were determined as a function of temperature and applied field magnitude, and compared with bulk crystals and vacuum-deposited single crystalline (epitaxial) thin films as well as manganite nanostructures reported in the literature. Both films display large values of colossal magnetoresistance at around room temperature. Significantly, the magnetoresistance in (100) La0.7Sr0.3MnO3 thin film is

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Effect of pressure on the global and local properties of cubic perovskite crystals Tarik Ouahrani1, I Merad-Boudia1, H Baltache2, R Khenata2,3 and Z Bentalha1 1

L aboratoire de Physique Théorique, Département de Physique, École Préparatoire Sciences et Techniques, BP 230, 13000 Tlemcen, Algeria

2

L aboratoire de Physique Quantique et de Modélisation Mathématique (LPQ3M), Université de Mascara, 29000 Mascara, Algeria

3

epartment of Physics and Astronomy, Faculty of Science, King Saud University, D PO Box 2455, Riyadh 11451, Saudi Arabia

in device performance. The dominant degradation mechanism is the growth of the donor–acceptor complex with time, which not only reduces the effective surface area but also hampers the charge separation. The little change in VOC and the significant change in JSC suggest that once the LiF/Al electrode is improved, one must modify the structure either by introducing a thin layer of high-molecular-weight P3HT between PEDOT:PSS (poly(3,4-ethylenedioxythiopene) poly(styrenesulfonate)) and photoactive P3HT:PCBM layers or by introducing an optimized content of P3HT nanofibrils/nanoparticles into the P3HT:PCBM blend. The best structure was found to be ITO/PEDOT:PSS/P3HT:PCBM/LiF/Al and it can be improved by the above two methods.


2011 Phys. Scr. 84 025704 Abstract The influence of pressure on the structural, elastic, thermal and bonding properties of four perovskite-type oxides AMO3 is studied from the point of view of the quantum theory of atoms in molecules. Ab initio investigations are performed by means of the full-potential linear augmented plane-wave method as implemented in the wien2k code. The integrated basin charges resulting from the topological analysis of electronic density provide a partition of the bulk modulus and compressibility into atomic contributions. Special attention is paid to the nonlinear behaviour of the local bonding properties.

Interdisciplinary physics and related areas of science and technology

Role of donor–acceptor domain formation and interface states in initial degradation of P3HT:PCBM-based solar cells Swati Arora1, Satish Kumar Rajouria1, Pankaj Kumar2, P K Bhatnagar3, Manoj Arora4 and R P Tandon5 1

epartment of Physics, Zakir Husian College, University of Delhi, Delhi-110002, D India

2

National Physical Laboratory, New Delhi, India

3

epartment of Electronics Science, South Campus, University of Delhi, D Delhi-110016, India

4

Department of Physics, Ramjas College, University of Delhi, Delhi-110007, India

5

Department of Physics and Astrophysics, University of Delhi, Delhi-110007, India

Synthesis and characterization of Cu doped cobalt oxide nanocrystals as methane gas sensors Z Sheikhi Mehrabadi1, A Ahmadpour1, N Shahtahmasebi2 and M M Bagheri Mohagheghi3 1

anotechnology Research Center, Department of Chemical Engineering, Ferdowsi N University of Mashhad, Mashhad, Iran

2

anotechnology Research Center, Department of Physics, Ferdowsi University of N Mashhad, Mashhad, Iran

3

School of Physics, Damghan University, Damghan, Iran


2011 Phys. Scr. 84 015801 Abstract In this paper, nanoparticles of copper–cobalt compound oxide have been prepared by the sol–gel technique with different mole ratios of Cu/Co (ranging from 0.05 to 0.15) for the detection of methane gas, which is chemically a very stable hydrocarbon. The structural properties and morphology of the powders were studied by x-ray diffraction (XRD), Fourier transform infrared spectroscopy and transmission electron microscopy (TEM). By XRD analysis, we confirm that Co3O4 and (CuO0.3CoO0.7) Co2O4 phases are formed and mean grain size is decreased with increasing Cu doping (from 28 to 24 nm). On the basis of TEM images, it is found that these particles possess a cubic structure with nearly uniform distribution. Also, gas-sensing measurements reveal that the optimal operating temperature is 300 °C, that the use of Cu as a dopant improved the sensing properties of cobalt oxide and that the sensitivity increased considerably with Cu concentration. The best sensitivity properties of nanosensors have been found at the mole ratios of Cu/Co of 0.125 and 0.15.


2011 Phys. Scr. 84 055702 Abstract This work is devoted to identifying the degradation mechanism in various structures of a poly(3-hexylthiophene) (P3HT):6,6-phenyl C61-butyric acid methyl ester (PCBM)-based solar cell. We have tried to identify the dominant initial degradation mechanism on the basis of experimental studies carried out on different structures of an organic solar cell. It is known that many of these problems can be solved by means of the following: using proper electrodes and a suitable annealing temperature and duration, improving the morphology of the active film and maintaining a donor–acceptor phase-segregated ordered network as far as possible. The present studies have been carried out both in the dark and under illumination, and it is suggested that initial degradation plays a key role

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Physica Scripta

Geophysics, astronomy and astrophysics

Lorentz-covariant quantum transport and the origin of dark energy Arne Bergstrom B&E Scientific Ltd, Seaford BN25 4PA, UK

Cosmic microwave background radiation in an inhomogeneous spherical space R Aurich1, P Kramer2 and S Lustig1 1

Institut für Theoretische Physik, Universität Ulm, Albert-Einstein-Allee 11, D-89069 Ulm, Germany

2

Institut für Theoretische Physik der Universität, Auf der Morgenstelle 14, D-74076 Tübingen, Germany



2011 Phys. Scr. 83 045301

2011 Phys. Scr. 84 055901

Abstract A possible explanation for the enigma of dark energy, responsible for about 76% of the mass–energy of the universe, is obtained by requiring only that the rigorous continuity equation (the Boltzmann transport equation) for quanta propagating through space should have the form of a Lorentzcovariant and dispersion-free wave equation. This requirement implies (i) properties of space–time that an observer would describe as uniform expansion in agreement with Hubble’s law and (ii) that the quantum transport behaves like in a multiplicative medium with multiplication factor ν=2. This inherent, essentially explosive multiplicity of vacuum, caused by the requirement of Lorentz covariance, is suggested as a potential origin of dark energy. In addition, it is shown (iii) that this requirement of Lorentzcovariant quantum transport leads to an apparent accelerated expansion of the universe.

Abstract We analyse the cosmic microwave background (CMB) radiation in spherical three-spaces with nontrivial topology. The focus is on an inhomogeneous space which possesses observer-dependent CMB properties. The suppression of the CMB anisotropies on large angular scales is analysed with respect to the position of the CMB observer. The equivalence of a lens space to a Platonic cubic space is shown and used for the harmonic analysis. We give the transformation of the CMB multipole radiation amplitude as a function of the position of the observer. General sum rules are obtained in terms of the squares of the expansion coefficients for invariant polynomials on the three-sphere.

Ionospheric perturbations associated with two recent major earthquakes (M>5.0) S Priyadarshi, S Kumar and A K Singh Atmospheric Research Laboratory, Department of Physics, Banaras Hindu University, Varanasi 221005, India E-mail: [email protected]

2011 Phys. Scr. 84 045901 Abstract In this paper, dual-frequency GPS data recorded at Varanasi (geographic latitude 25°16' N, longitude 82°59' E) have been analyzed to study the ionospheric perturbations in total electron content (TEC) due to two recent major earthquakes (M>5.0) whose main shocks occurred on 25 February and 12 March 2010. A monthly median of the TEC and associated interquartile range, upper bound and lower bound are utilized as a reference to identify abnormal signals during these two earthquakes. The results show anomalous depletions in the TEC. These pre-earthquake ionospheric anomalies appear within 6 days prior to the earthquakes. We have also analyzed the ELF and VLF spectra observed from the DEMETER microsatellite above the epicenter of the earthquake to support the ionospheric anomalies prior to the earthquakes. A possible mechanism responsible for the ionospheric anomalies due to earthquakes is also discussed.

Comments section (CAMOP)

Dimensions, nodes and phases in quantum numbers A R P Rau Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803, USA E-mail: [email protected]

2011 Phys. Scr. 83 018101 Abstract Students of quantum mechanics encounter discrete quantum numbers in a somewhat incoherent and bewildering number of ways. For each physical system studied, quantum numbers seem to be introduced in their own specific way, some enumerating from 1 and others from 0, without a common uniting thread. This essay presents a point of view that builds on dimensions, boundary conditions and various inputs that, while known, are often not brought together to present a simple, consistent picture. At the same time, some surprisingly sophisticated connections are also made.

Testing Lorentz symmetry with atoms and light Neil Russell Physics Department, Northern Michigan University, Marquette, MI, USA E-mail: [email protected]

2011 Phys. Scr. 84 038101 Abstract This article reports on the Fifth Meeting on CPT and Lorentz Symmetry, CPT ’10, held at the end of June 2010 in Bloomington, Indiana, USA. The focus is on recent tests of Lorentz symmetry using atomic and optical physics. www.physica.org

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Physica Scripta

Optical tomography of Fock state superpositions S N Filippov1,2 and V I Man’ko1,2 1

Moscow Institute of Physics and Technology, Moscow, Russia

2

P N Lebedev Physical Institute, Moscow, Russia


2011 Phys. Scr. 83 058101 Abstract We consider optical tomography of photon Fock state superpositions (FSS) in connection with recent experimental achievements. The emphasis is put on the fact that it suffices to represent the measured tomogram as a main result of the experiment. We suggest a test for checking the correctness of experimental data. Explicit expressions for optical tomograms of FSS are given in terms of Hermite polynomials. Particular cases of vacuum and low-photon-number state superposition are considered and the influence of thermal noise on state purity is studied.

On multiple adsorptions of hydrogen atoms on graphene Benjamin J Irving, Anthony J H M Meijer and Dean Morgan Department of Chemistry, University of Sheffield, Sheffield S3 7HF, UK E-mail: [email protected]

2011 Phys. Scr. 84 028108 Abstract First-principles calculations using the Vienna Ab Initio Simulation Package (VASP) have been performed in order to scrutinize the hydrogen–graphene interaction. Emphasis has been placed on how surface relaxation and the prior chemisorption of one, two and three hydrogen atoms on graphene affect the adsorption properties of an encroaching gas phase hydrogen atom. Chemisorption at the para site was found to be barrierless, while it has been shown that a stable ortho adsorbate can form directly from the gas phase. Adsorption of the third and fourth H atoms was found in all cases to have a significant barrier. The resultant minimum energy structures show a reasonable agreement with scanning tunneling microscopy images obtained by Hornekær et al (2007 Chem. Phys. Lett. 446 237).

Comments section (CCMP)

High-temperature superconductivity: the explanation A S Alexandrov Department of Physics, Loughborough University, Loughborough LE11 3TU, UK E-mail: [email protected]

2011 Phys. Scr. 83 035201 Abstract Soon after the discovery of the first high-temperature superconductor by Georg Bednorz and Alex Müller in 1986, the late Sir Nevill Mott in answering

24

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his own question ‘Is there an explanation?’ (1987 Nature 327 185) expressed the view that the Bose–Einstein condensation (BEC) of small bipolarons, predicted by us in 1981, could be the one. Several authors then contemplated BEC of real-space tightly bound pairs, but with a purely electronic mechanism of pairing rather than with an electron–phonon interaction (EPI). However, a number of other researchers criticized the bipolaron (or any real-space pairing) scenario as incompatible with some angle-resolved photoemission spectra, with experimentally determined effective masses of carriers and unconventional symmetry of the superconducting order parameter in cuprates. Since then, the controversial issue of whether EPI is crucial for high-temperature superconductivity or is weak and inessential has been one of the most challenging problems of contemporary condensed matter physics. Here I outline some developments in the bipolaron theory suggesting that the true origin of hightemperature superconductivity is found in a proper combination of strong electron–electron correlations with a significant finite-range (Fröhlich) EPI, and that the theory is fully compatible with key experiments.

The pairing mechanism of high-temperature superconductivity: experimental constraints Guo-meng Zhao1,2 1

epartment of Physics, Faculty of Science, Ningbo University, Ningbo, People’s D Republic of China

2

epartment of Physics and Astronomy, California State University, Los Angeles, D CA 90032, USA


2011 Phys. Scr. 83 038302 Abstract Developing a theory of high-temperature superconductivity in copper oxides is one of the outstanding problems in physics. It is a challenge that has defeated theoretical physicists for more than 20 years. Attempts to understand this problem are hindered by the subtle interplay among a few mechanisms and the presence of several nearly degenerate and competing phases in these systems. Here, we present some crucial experiments that place essential constraints on the pairing mechanism of high-temperature superconductivity. The observed unconventional oxygen-isotope effects in cuprates have clearly shown strong electron–phonon interactions and the existence of polarons and/or bipolarons. Angle-resolved photoemission and tunneling spectra have provided direct evidence for strong coupling to multiple-phonon modes. In contrast, these spectra do not show strong coupling features expected for magnetic resonance modes. Angleresolved photoemission spectra and the oxygen-isotope effect on the antiferromagnetic exchange energy J in undoped parent compounds consistently show that the polaron binding energy is about 2 eV, which is over one order of magnitude larger than J = 0.14 eV. The normal-state spinsusceptibility data of hole-doped cuprates indicate that intersite bipolarons are the dominant charge carriers in the underdoped region, while the component of Fermi-liquid-like polarons is dominant in the overdoped region. All the experiments for testing the gap or order-parameter symmetry consistently demonstrate that the intrinsic gap (pairing) symmetry for the Fermi-liquid-like component is anisotropic s-wave and the order-parameter symmetry of the Bose–Einstein condensation of bipolarons is d-wave.

Physica Scripta

Comments section (CFRP)

Foundations of quantum mechanics?

Entanglement dynamics of a bipartite system in squeezed vacuum reservoirs Smail Bougouffa1 and Awatif Hindi2

Göran Lindblad

1

Department of Theoretical Physics, Royal Institute of Technology, SE-106 91, Stockholm, Sweden

epartment of Physics, Faculty of Science, Taibah University, PO Box 30002, D Madinah, Saudi Arabia

2

P hysics Department, College of Science, PO Box 22452, King Saud University, Riyadh 11495, Saudi Arabia


2011 Phys. Scr. 84 018501 Abstract Does quantum mechanics have unsolved foundational problems? Is there a dividing line between the quantum and classical descriptions of the world? In this paper, I give an elementary introduction to the mathematical aspects of quantum and classical models which have prompted such questions.

Topical issue (T143)

Entanglement dynamics of two independent cavity-embedded quantum dots


2011 Phys. Scr. T143 014006 Abstract Entanglement plays a crucial role in quantum information protocols; thus the dynamical behavior of entangled states is of great importance. In this paper, we suggest a useful scheme that permits a direct measure of entanglement in a two-qubit cavity system. It is realized through cavityQED technology utilizing atoms as flying qubits. To quantify entanglement we use the concurrence. We derive the conditions that ensure that the state remains entangled in spite of the interaction with the reservoir. The phenomenon of entanglement sudden death in a bipartite system subjected to a squeezed vacuum reservoir is examined. We show that the sudden death time of the entangled states depends on the initial preparation of the entangled state and the parameters of the squeezed vacuum reservoir.

B Bellomo1, G Compagno1, R Lo Franco1, A Ridolfo2 and S Savasta2 1

NISM and Dipartimento di Scienze Fisiche ed Astronomiche, Università di Palermo, C Via Archirafi 36, 90123 Palermo, Italy

2

ipartimento di Fisica della Materia e Ingegneria Elettronica, Università di Messina, D Via Salita Sperone 31, I-98166 Messina, Italy


2011 Phys. Scr. T143 014004 Abstract We investigate the dynamical behavior of entanglement in a system made of two solid-state emitters, as two quantum dots, embedded in two separated microcavities. In these solid-state systems, in addition to the coupling with the cavity mode, the emitter is coupled to a continuum of leaky modes providing additional losses and is also subjected to a phononinduced pure dephasing mechanism. We model this physical configuration as a multipartite system composed of two independent parts each containing a qubit embedded in a single-mode cavity, exposed to cavity losses, spontaneous emission and pure dephasing. We study the time evolution of entanglement of this multipartite open system, finally applying this theoretical framework to the case of currently available solid-state quantum dots in microcavities.

A smooth, holographically generated ring trap for the investigation of superfluidity in ultracold atoms Graham D Bruce, James Mayoh, Giuseppe Smirne, Lara Torralbo-Campo and Donatella Cassettari Scottish Universities Physics Alliance, School of Physics and Astronomy, University of St Andrews, St Andrews, Fife KY16 9SS, UK E-mail: [email protected]

2011 Phys. Scr. T143 014008 Abstract We discuss the suitability of holographically generated optical potentials for the investigation of superfluidity in ultracold atoms. By using a spatial light modulator and a feedback enabled algorithm, we generate a smooth ring with variable bright regions that can be dynamically rotated to stir ultracold atoms and induce superflow. We also comment on its future integration into a cold atom experiment.

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Physica Scripta

Entanglement in two-mode continuous variable open quantum systems Aurelian Isar

At the borderline between atomic and nuclear physics: two-body β-decay of highly charged ions

National Institute of Physics and Nuclear Engineering, PO Box MG-6, BucharestMagurele, Romania

Yuri A Litvinov1,2, Fritz Bosch2, Christophor Kozhuharov2, Xinwen Ma3, Thomas Stöhlker2,4, Nicolas Winckler1 and Takayuki Yamaguchi5


1

Max-Planck Institut für Kernphysik, 69117 Heidelberg, Germany

2

GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany

3

Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, People’s Republic of China

4

P hysikalisches Institut, Ruprecht-Karls-Universität Heidelberg, 69120 Heidelberg, Germany

5

Saitama University, 338-8570 Saitama, Japan

2011 Phys. Scr. T143 014012 Abstract In the framework of the theory of open systems based on completely positive quantum dynamical semigroups, we present a description of continuous-variable entanglement for a system consisting of two noninteracting modes embedded in a thermal environment. By using the Peres–Simon necessary and sufficient criterion for the separability of two-mode Gaussian states, we describe the evolution of entanglement in terms of the covariance matrix for Gaussian input states. For all values of the temperature of the thermal reservoir, an initial separable Gaussian state remains separable for all times. In the case of an entangled initial Gaussian state, entanglement suppression (entanglement sudden death) takes place for non-zero temperatures of the environment. Only for zero temperature of the thermal bath, the initial entangled state remains entangled for finite times. We also show that, independent of its type, namely separable or entangled, the initial state evolves asymptotically to an equilibrium state that is always separable.

Topical issue (T144)

An ECR ion source-based low-energy ion accelerator: development and performance A N Agnihotri1, A H Kelkar1,3, S Kasthurirangan1,2, K V Thulasiram1, C A Desai1, W A Fernandez1 and L C Tribedi1


2011 Phys. Scr. T144 014001 Abstract In this paper, we discuss the radioactive decay of highly charged ions. There are several motivations for performing this kind of research. One of them is that stellar nucleosynthesis proceeds at high temperatures and therefore the involved atoms are highly ionized. Highly charged ions also offer the possibility of addressing the decay of well-defined quantum-mechanical systems such as, for example, one-electron ions, where all the interactions with other electrons are excluded. These studies can be performed solely at ion storage rings or ion traps, where the high atomic charge states can be preserved for extended periods of time. Although we have focused on experiments conducted at the storage ring ESR of GSI, we have tried to describe the general requirements for such experiments.

Configuration and calibration of a flat field grating spectrometer in the wavelength range 7–60 Å with a Manson ultrasoft x-ray source

1

Tata Institute of Fundamental Research, Mumbai 400005, India

Y Yang, Z Shi, Z Fei, X Jin, J Xiao, R Hutton and Y Zou

2

Institute of Chemical Technology, Matunga, Mumbai 400019, India

3

Present address: MPIKP, Heidelberg, Germany

The Key Laboratory of Applied Ion Beam Physics, Ministry of Education, People’s Republic of China


Shanghai EBIT Laboratory, Institute of Modern Physics, Fudan University, Shanghai, People’s Republic of China

2011 Phys. Scr. T144 014038


Abstract Electron cyclotron resonance (ECR) ion sources produce low-energy, highly charged ions. A new 14.5 GHz ECR-based low-energy ion accelerator facility has been developed. The ion source involves a plasma chamber (‘supernanogan’) surrounded by permanent magnets that provide a suitable magnetic field. The entire assembly including the ion source and the analyzing magnet is mounted on a 400 kV deck. A LabVIEW-based command and control system has been developed for the beamline. In addition, wireless communication has been installed to operate the machine in high voltage. The charge state distribution of several ions (He, N2, O2, Ne, Ar and Xe) has been measured. For Ar and Xe, the maximum charge states measured were 16+ and 29+, respectively. A direct x-ray measurement for plasma diagnostics was also initiated.

26

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2011 Phys. Scr. T144 014064 Abstract An ultrasoft x-ray and extreme ultraviolet spectrometer built and calibrated in the wavelength range of 7–60 Å is reported here. Details of the alignment of this flat field spectrometer with both a laser and a telescope are presented. The light path function rather than a standard calibration function, i.e. a polynomial function, is introduced as the fit function, which gives good agreement with the spectrometer design values and makes the calibration more reliable when extended to the region outside the points used for calibration, compared with a standard calibration function. The calibration results of a Manson ultrasoft x-ray source (model 2) with source targets of Cu, Fe and Ti are presented with all the peaks marked.

Cover gallery ISSN 0031-8949

ISSN 0031-8949

February 2011

Volume 83

PAPERS

ion approach

PAPERS GENERAL PHYSICS

GENERAL PHYSICS

Multisoliton interaction in discrete alpha-helical proteins with interspine coupling M M Latha and S S Veni

045001

Homodyne estimation of quantum state purity by exploiting the covariant uncertainty relation V I Man’ko, G Marmo, A Porzio, S Solimeno and F Ventriglia

035002

Coulomb screening of 2D massive Dirac fermions Jia-Ning Zhang

045002

The Schmidt number as a universal entanglement measure J Sperling and W Vogel


An Ainternational journal for experimental and theoretical physics new generalized fifth-order nonlinear integrable equation

Ismagil T Habibullin and Elena V Gudkova

Abdul-Majid Wazwaz

The construction, properties and applications of a new bipartite coherent-entangled state in the two-mode Fock space Xiang-Guo Meng, Ji-Suo Wang and Bao-Long Liang

www.physica.org

Nonclassical properties and generation of excited entangled coherent states of motion of a trapped ion Zhongjie Wang

025008

Multiplicative noise-induced vibrational resonance in a monostable system with one high-frequency and two low-frequency forces Feng Guo

025009

Stability of embedded solitons in higher-order NLS equations Debabrata Pal, Sk Golam Ali and B Talukdar

www.physica.org Exact analytic solutions generated from stipulated Morse and trigonometric Scarf potentials

035006

N Saikia and S A S Ahmed 035007

Some Lagrangians for systems without a Lagrangian M C Nucci and P G L Leach

035008

Noise enhanced stability effect in a metastable system with two different kinds of time delays and cross-correlated noises Zheng-Lin Jia and Dong-Cheng Mei

035201

Thermal phase transition in 93−98 Mo nuclei Z Kargar and F Mosaleh

035401

Kinetic description of self-field effects on laser and betatron emission in wiggler-pumped ion-channel free electron lasers M Alimohamadi, H Mehdian and A Hasanbeigi

NUCLEAR PHYSICS

045006

On the spontaneous ordering of the mixed-spin Ising square lattice with singly and triply decorated bonds

Featured in Jthis issue J Kiˇssˇová and Streˇcka

Comments on Condensed Matter Physics Anomalous diffusion in a symbolic model

045007

H V Ribeiro, E K Lenzi, R S Mendes and P A Santoro

www.physica.org Fidelity of structured amplitude-damping channels

045008

Jing Wang, Li Jiang, Han Zhang, Hanzhuang Zhang and Liquan Zhang 045009

Nonlinear excitations in a continuous bi-inductance electrical line Fran¸cois Beceau Pelap, Innocent Tatsinkou and Anaclet Fomethe

045301

The mechanical, electronic structure and thermodynamic properties of B2-based AgRE studied from first-principles Xiaoma Tao, Hongmei Chen, Xingxiu Li, Yifang Ouyang and Shuzhi Liao

045302

The Stark effect in autoionizing doubly excited states of helium below the He+ (n = 2) threshold Spyros I Themelis

Forbidden transitions in excitation by electron impact in Co3+ : an R-matrix approach V Stancalie

035501

Drift-Alfvén eigenmodes in inhomogeneous electron–positron–ion plasmas Q Haque, S Yamin and Ali Ahmad

045401

Effect of higher-order waves in parametric oscillatory instability in optical cavities M Abdi and A R Bahrampour

Relativistic configuration interaction calculations on Kα x-ray satellites of krypton Li Zhang, Gang Jiang, Lianghuan Hao and Banglin Deng

035502

025303

Multiple backscattering on monoelemental materials and albedo factors of 279, 320, 511 and 662 keV gamma photons Arvind D Sabharwal, B S Sandhu and Bhajan Singh

Self-modulation instability of an intense laser beam in a magnetized pair plasma Hua-Ying Chen, San-Qiu Liu and Xiao-Qing Li

045501

035503

Parametric decay of whistler waves in electron magnetohydrodynamics Lennart Stenflo and Gert Brodin

The 3+1 dimensional Kadomtsev–Petviashvili Burgers’ equation in non-uniform dusty plasmas Li-Ping Zhang, Ju-Kui Xue and Li-Hua Yuan

045502

025304

Studies on the full vibrational energies and dissociation limits of some electronic states of Kr2+ and Xe2+ diatomic molecular ions Qunchao Fan, Weiguo Sun, Huidong Li and Hao Feng

035504

Dynamic evolution of the resistive wall mode in flowing plasmas Longxi Chen and Zhiwei Ma

Transport of fast electrons in lower hybrid current drive plasmas in the HT-7 tokamak Z Y Chen, D Fang, F Dai, Z Q Duan, J X Zhu, W M Sun, B N Wan and Y J Shi

045503

035505

Acoustic solitons in magnetized quantum electron–positron plasmas S Mahmood, N Akhtar and H Ur-Rehman

Experimental and theoretical studies of the direct-current breakdown voltage in argon at micrometer separations M Klas, Sˇ Matejˇc´ık, B Radjenović and M Radmilović-Radjenović

045601

Statistical derivation of modified hydrodynamic equations for nanotube flows I Yu Popov

ey fluid

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ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS AND FLUID DYNAMICS

PHYSICS OF GASES, PLASMAS AND ELECTRIC DISCHARGES

025301 025302

ine–Gordon equation

Volume 83 Number 4 April 2011 A journal of the Royal Swedish Academy of Sciences published by IOP Publishing

ATOMIC AND MOLECULAR PHYSICS


Scattering of a focused Gaussian beam by an axisymmetric particle with a nonconcentric spherical core E E M Khaled and M E M Aly

Multiparty quantum secret sharing based on GHZ states

Tzonelih Cheng-Chieh Volume 83 Hwang, Number 3 MarchHwang 2011 and Chuan-Ming Li

045005A journal Extended transformations high-order systems in of theGalilean Royal Swedish Academyfor of Sciences published bytwo IOPintegrable Publishinghierarchies Da-jun Zhang, Deng-yuan Chen and Liu-feng Hu

045001–047004

Synchronization of chaos in two mesoscopic shunted resistive–capacitive–inductive Josephson junctions by means of a nonlinear van der Pol oscillator Sameer Al-Khawaja

025007

045004

Quantum diffusion

Volume 83 Tsekov Number 2 February 2011 Roumen

A journal of the Royal Swedishboundary Academyconditions of Sciences publishedmechanics by IOP Publishing 035005 Oscillating and rotating in quantum Cem Yuce and Zalihe Ozcakmakli

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Fault-tolerant quantum secret sharing against collective noise Yu-Guang Yang, Yi-Wei Teng, Hai-Ping Chai and Qiao-Yan Wen

Volume 83 Number 1 January 2011 Entanglement concentration using a path–spin hybrid-entangled state A journal of the RoyalXiao-Qiang Swedish Academy Sciences Liu-Yong Cheng, Shao and of Shou Zhang published by IOP Publishing

Vol 83, No 4

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Vol 83, No 3

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the classical Ising chain

April 2011

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THE PHYSICS OF ELEMENTARY PARTICLES AND FIELDS

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Number 4

Resolution of the Klein paradox A D Alhaidari

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dial basis functions

Volume 83

Quantization rule solution to the Hulthén potential in arbitrary dimension with a new approximate scheme for the centrifugal term Sameer M Ikhdair and Jamal Abu-Hasna

025001–025902

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Physica Scripta

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Vol 83, No 2

or a pseudoharmonic

015001–018101

nterval neural networks

March 2011

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Number 3

PAPERS

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nd the Gauss–Bonnet

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PHYSICS OF GASES, PLASMAS AND ELECTRIC DISCHARGES

CONDENSED MATTER: STRUCTURAL, MECHANICAL AND THERMAL PROPERTIES

Volume 83, issue 2

06/01/2011 09:43

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Cover image taken from AsiehSadat Kazemi et al 2011 Phys. Scr. 83 015801

Volume 84

PAPERS

via an entangled coherent quantum network An Communication international journal for experimental and theoretical physics A El Allati, Y Hassouni and N Metwally

065003

065005

Gap and out-gap solitons in modulated systems of finite length: exact solutions in the slowly varying Featured in this issue envelope limit

Self-adjoint extensions and spectral analysis in the generalized Kratzer problem M C Baldiotti, D M Gitman, I V Tyutin and B L Voronov

065008

Delay-improved signal propagation in globally coupled bistable systems J H Yang and X B Liu

065009

Harmonic response of a class of finite extensibility nonlinear oscillators M Febbo

065010

Sinc and solitary wave solutions to the generalized Benjamin–Bona–Mahony–Burgers equations Marwan Alqruan and Kamel Al-Khaled

065011

Synchronization of modified Colpitts oscillators with structural perturbations Soup Tewa Kammogne and H B Fotsin

ctor laser with optical

015005

Accurate analytic approximation to the nonlinear pendulum problem

015006

Vibration control for the parametrically excited van der Pol oscillator by nonlocal feedback Attilio Maccari

015007

New stability and stabilization criteria for fuzzy neural networks with various activation functions K Mathiyalagan, R Sakthivel and S Marshal Anthoni

www.physica.org M Turkyilmazoglu

015008

The time-dependent forced anisotropic oscillator in noncommutative phase space Mai-Lin Liang and Qian Chen

015009

Electromagnetic potentials without gauge transformations A Chubykalo, A Espinoza and R Alvarado Flores

015010

Two schemes of remote preparation of a four-particle entangled W state via a six-qubit maximally entangled state Xin-Wei Zha and Hai-Yang Song

015011

Stochastic quantization method for spinless relativistic particles in two wave fields Nadia Chine and Lyazid Chetouani


bedded in an anisotropic

Elastic scattering of positrons from hydrogen atoms with exponential cosine-screened Coulomb potentials Arijit Ghoshal and Y K Ho

065302

Quasirelativistic treatment of spectral characteristics of W37+ ˇ P Bogdanovich, O Rancova and A Stikonas

nergy–momentum tensor 065401

065402

near the linear stability

065403

zyński

015201

Characteristics of multiplicity distribution of target fragments in forward and backward hemispheres in high-energy nucleus–nucleus interactions Dipak Ghosh, Argha Deb and Swarnapratim Bhattacharyya

015301

Resonance transitions in Rh VIII, Pd IX, Ag X and Cd XI spectra A N Ryabtsev and E Ya Kononov

015302

Multiconfiguration Dirac–Fock calculations of transition probabilities of some tungsten ions Feng Hu, Chuangke Wang, Jiamin Yang, Gang Jiang and Lianghuan Hao

Hydrodynamic view of electrodynamics: energy rays and electromagnetic effective stress Chia-Chun Chou and Robert E Wyatt

On the interaction between two two-level atoms and a two mode cavity field in the presence of detuning and cross-Kerr nonlinearity N H Abdel-Wahab and M F Mourad


Bibliographic codes CODEN: PHSTBO 84 (1) 015001–019802 (2011) ISSN: 0031-8949

Volume 83, issue 6

05/05/2011 13:52


Cover image taken from Madalina Boca and Andreea Oprea 2011 Phys. Scr. 83 055404

Hidden rotational symmetry in a generalized Ising model with rectangular symmetry Hai-Yao Deng and Kaige Hu

025301

Verification of the validity of the short-pulse approximation for one-dimensional Rydberg atoms T Kopyciuk and M Grajek

025302

Efficient extension of the trapping lifetime of single atoms in an optical tweezer by laser cooling Jun He, Baodong Yang, Tiancai Zhang and Junmin Wang

025401

Power-flow formulation of a ray approach to the modelling of inhomogeneous waves M Tereshchenko, F Castejón, S Pavlov and A Cappa

025402

The deflection of bright spatial solitons in a biased non-centrosymmetric two-photon photovoltaic photorefractive crystal due to first-order diffusion and higher order drift S Shwetanshumala, S Konar, N Asif and A Biswas

025403

Mixed convection boundary-layer flow about an isothermal solid sphere in a nanofluid L Tham, R Nazar and I Pop

Number 5

Cover image taken from R J Zhou et al 2011 Phys. Scr. 84 015501

November 2011

Volume 84

Number 6

December 2011

065001

Exact solutions of a two-dimensional cubic–quintic discrete nonlinear Schrödinger equation Avinash Khare, Kim Ø Rasmussen, Mogens R Samuelsen and Avadh Saxena

045002

Universal quantum computing with nanowire double quantum dots

065002

The Anderson localization problem, the Fermi–Pasta–Ulam paradox and the generalized diffusion approach

045003

An analysis of the applications of the modified Kratzer potential Ali Akbar Babaei-Brojeny and Mojtaba Mokari

055003

Illarion Dorofeyev

065003

Nonclassical properties of the integrability condition of the time-dependent SU(2) quantum system M Sebawe Abdalla and E M Khalil

045012

045013 045014 045015

Abdul-Majid Wazwaz

055007

R Rakkiyappan, P Balasubramaniam and K Balachandran 055008

Notes on thermodynamics in special relativity M Przanowski and J Tosiek

055101

Interaction of orientable object fields with gauge fields D M Gitman and A L Shelepin

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Subquantum nonlocal correlations induced by the background random field Andrei Khrennikov Cryptanalysis of quantum secret sharing based on GHZ states Xiao-Fen Liu and Ri-Jing Pan Scalar field reconstruction of power-law entropy-corrected holographic dark energy Esmaeil Ebrahimi and Ahmad Sheykhi

045018

Three-dimensional quantum key distribution in the presence of several eavesdroppers M Daoud and H Ez-zahraouy

reaction

065007

Soliton solutions of the dispersive sine-Gordon and the dispersive sinh-Gordon equations with fourth spatial or spatio-temporal derivatives Abdul-Majid Wazwaz

065008

Analytical treatment of the two-body spinless Salpeter equation with the Hulthén potential S Zarrinkamar, A A Rajabi, H Hassanabadi and H Rahimov

065009

Generation of a three-dimensional N-atom GHZ state based on optical-fiber-connected cavity quantum electrodynamics Y Q Zhang, Z Jin, S Zhang, K H Yeon and S C Yu

065010

Entanglement dynamics of two electron-spin qubits in a strongly detuned and dissipative quantum-dot-cavity system Shao-Hua Xiang, Xiao-Peng Deng, Ke-Hui Song, Wei Wen and Zhen-Gang Shi

065011 065012

Measurements of hyperfine structure in 51 V II N M R Armstrong, S D Rosner and R A Holt

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Impact of the depth of the wells and multifractal analysis on stochastic resonance in a triple-well system S Arathi and S Rajasekar


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Effects of external bounded noise on nonlinear dynamics of plasma density C Nono Dueyou Buckjohn, M Siewe Siewe, C Tchawoua and T C Kofane

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The eigenvalues and eigenstates of the effective Hamiltonian in the interaction of an atom with both classical gravity and quantum radiation M Mohammadi

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Bandgap calculation of two-dimensional mixed solid–fluid phononic crystals by Dirichlet-to-Neumann maps Feng-Lian Li, Yue-Sheng Wang and Chuanzeng Zhang

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(Continued on inside back cover) Bibliographic codes CODEN: PHSTBO 84 (5) 055001–059801 (2011) ISSN: 0031-8949

Volume 84, issue 4 PS84-5cover-UK.indd 2-4

Cover image taken from Sandip V Kamat et al 2011 Phys. Scr. 84 045801

12/10/2011 10:14

Single-electron capture from helium by fast protons R Samanta and M Purkait Studies on the full vibrational energies and dissociation energies of some halogen diatomic molecules Qunchao Fan, Weiguo Sun, Huidong Li and Hao Feng New even and odd parity levels of neutral praseodymium T I Syed, I Siddiqui, K Shamim, Z Uddin, G H Guthöhrlein and L Windholz ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS AND FLUID DYNAMICS

Solitons and their interactions in a tapered aorta Li-hua Zhao, Yue-yue Wang and Chao-qing Dai (Continued on inside back cover)


Volume 84, issue 5 PS84-6cover-UK.indd 2-4

04/11/2011 11:44

Cover image taken from M A Ahmed et al 2011 Phys. Scr. 84 055602

December 2011

Cover image taken from S Cheng et al 2011 Phys. Scr. 84 035006

Volume 84 Number 6 December 2011 A journal of the Royal Swedish Academy of Sciences published by IOP Publishing


November 2011

05/09/2011 11:31

October 2011

September 2011

(Continued on inside back cover)

A Ibort, V I Man’ko, G Marmo, A Simoni and F Ventriglia

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Volume 84, issue 3

On the determination of the time-scale of three-fragment emission in the 12.7 GeV using the polycarbonate track detector Makrofol ˇ Svetislav Savović, Zivojin Todorović, Alexandar Djordjevich and Stevan Jokić

4 He+238 U


Nonadditivity of quantum capacities of quantum multiple-access channels and the butterfly network Peng Huang, Guangqiang He, Jun Zhu and Guihua Zeng

The chaotic atom model via a fractal approximation of motion M Agop, P Nica, S Gurlui, C Focsa, D Magop and Z Borsos

www.physica.org A pedagogical presentation of a C -algebraic approach to quantum tomography

065006

NUCLEAR PHYSICS

Combined effects of asymmetry and noise correlation on the noise-enhanced stability phenomenon in a bistable system Dong-Cheng Mei, Zheng-Lin Jia and Can-Jun Wang

045016

Delay-dependent global asymptotic stability criteria for genetic regulatory networks with time delays in

www.physica.org the leakage term

ELEMENTARY PARTICLES AND FIELDS

Protecting the squeezing of a two-level system by detuning in non-Markovian environments Xing Xiao, Mao-Fa Fang and Yan-Min Hu

045017


Kadomtsev–Petviashvili equation Comments on Astrophysics and Cosmology

On the exact solutions of a nano boundary layer problem using the simplest equation method Abdelhalim Ebaid and Nader Y Abd Elazem

065001–069502

Optimization analysis of the performance of an irreversible Ericsson refrigeration cycle in the micro/nanoscale Hao Wang, Guoxing Wu and Yueming Fu

045010

Distinct kinds multiple-soliton Featured inofthis issue solutions for a (3+1)-dimensional generalized B-type

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Self-similar analytical model of plasma expansion in a magnetic field H B Nersisyan, K A Sargsyan, D A Osipyan, M V Sargsyan and H H Matevosyan

84 Number 5 inNovember 2011 065004Volume Bifurcation and chaos a perturbed soliton equation with higher-order nonlinearity Jun Yu, Zhang and Guojuan Jinof Sciences published by IOP Publishing A journal of Rongbo the Royal Swedish Academy

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On Newton’s third law and its symmetry-breaking effects Volume Number 4 October 2011 Mario J84 Pinheiro

055001–059801

Magnetic operations: a little fuzzy mechanics? B Mielnik and A Ram´ırez

AnThermodynamic international journal for experimental and theoretical physics functions of fluctuating electromagnetic fields within a heterogeneous system

of the Royal Swedish Academy of Sciences published by IOP Publishing 055005 A journal The k-essence models and cosmic acceleration in generalized teleparallel gravity M Sharif and Shamaila Rani 055006

Cover image taken from Benjamin J Irving et al 2011 Phys. Scr. 84 028108

AnVinternational journal for experimental and theoretical physics N Kuzovkov Vol 84, No 5

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035001–038101

Synthetic multicellular oscillatory systems: controlling protein dynamics with genetic circuits www.physica.org Aneta Koseska, Evgenii Volkov and Jürgen Kurths

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Vol 84, No 4

Vol 84, No 3


045006Comments Entanglement swapping of a GHZ state a GHZ-like state on Atomic, Molecular andvia Optical Physics Chia-Wei Tsai and Tzonelih Hwang

05/08/2011 10:08

GENERAL PHYSICS

GENERAL PHYSICS

On the photon distribution of the two-mode squeezed chaotic state Jun Zhou, Hong-yi Fan and Jun Song

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PAPERS

PAPERS

Localized nonlinear wavepackets with radial–azimuthal modulated nonlinearity and an external potential Wei-Ping Zhong, Milivoj R Belić and Gaetano Assanto

045005

Comments on Atomic, Molecular and Optical Physics

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Relativistic two-dimensional H-like model atoms in an external magnetic field A Poszwa

055004


Volume 84, issue 2

30/06/2011 10:42

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045004Volume On a84 (2+1)-dimensional Madelung system Number 3 September 2011with logarithmic and with Bohm quantum potentials: Ermakov reduction A journal of the Royal Swedish Academy of Sciences published by IOP Publishing Colin Rogers and Hongli An

Volume 84 Number 2 August 2011 A journal of the Royal Swedish Academy of Sciences published by IOP Publishing

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055002

045011

nued on inside back cover)

The tanh and sine–cosine methods for higher order equations of Korteweg–de Vries type Marwan Alquran and Kamel Al-Khaled

025011

J-Matrix approach for the exponential-cosine-screened Coulomb potential I Nasser, M S Abdelmonem and Afaf Abdel-Hady

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The relaxation time of processes in a FitzHugh–Nagumo neural system with time delay Ailing Gong, Hua Wang and Chunhua Zeng

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PAPERS

unable frequency offset

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ating magnetic field wave

Synchronization analysis of complex dynamical networks with delayed and non-delayed coupling based on pinning control Song Zheng and Qinsheng Bi

Volume 84, issue 1

01/06/2011 14:58

Cover image taken from Ping Liu and Shutang Liu 2011 Phys. Scr. 83 065006

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ew (3 + 1)-dimensional

New higher-dimensional fifth-order nonlinear equations with multiple soliton solutions Abdul-Majid Wazwaz

025008


July 2011

June 2011

May 2011


Volume 83, issue 5

states of the isotonic

025007



-wave Boussinesq-class

Karl-Erik Thylwe and Staffan Linnæus

August 2011

inued on inside back cover)

Number 4

www.physica.org Semiclassical aspects and supersymmetry of bound Dirac states for central pseudo-scalar potentials

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015401

The Dirac–Yukawa problem in view of pseudospin symmetry Oktay Aydo˘gdu and Ramazan Sever



The existence and stability of incoherently coupled bright–dark soliton families in photorefractive polymers Qichang Jiang, Yanli Su, Xuanmang Ji and Jinlai Wang

Volume 84

025005


Propagation of shock waves in a viscous medium Harish C Yadav and R K Anand


A scheme for symmetrization verification Pedro Sancho

84 Number 1 state Julysolutions 2011 of the asymmetric Hulthén potential 025004Volume Scattering and bound Altu˘g of Arda, Aydo˘gdu and Ramazan Sever A journal the Oktay Royal Swedish Academy of Sciences published by IOP Publishing


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compact discretization of O(h ) for two-dimensional nonlinear triharmonic equations AnARinternational for experimental and theoretical physics K Mohanty, M K Jainjournal and B N Mishra

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83of the Number 6 June 2011 015004Volume l-states Manning–Rosen potential with an improved approximate scheme and Feynman path integral formalism A journal of the Royal Swedish Academy of Sciences published by IOP Publishing A Diaf and A Chouchaoui

Deterministic controlled-phase gate and preparation of cluster states via singly charged quantum dots in cavity quantum electrodynamics Tao Yu, Ai-Dong Zhu, Shou Zhang, Kyu-Hwang Yeon and Seong-Cho Yu

025002

015001–019802

Anti-synchronization between different chaotic complex systems

Ping Liu and Shutang Liu www.physica.org

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dynamical system with time delay Lu-Chun Du and Dong-Cheng Mei

065001–069802

065006 065007

Perturbation of dispersive topological solitons Stephen Johnson and Anjan Biswas

025001–029701

Comments on Atomic, and Optical Physics M Johansson, K Kirr, AMolecular S Kovalev and L Kroon

August 2011

Vol 84, No 2

Haibo Bao and Jinde Cao

015002

Vol 84, No 1

Volume 83 Number 5 May 2011 Robust state estimation for uncertain stochastic bidirectional associative memory networks with A journal of the Royal Swedish Academy of Sciences published by IOP Publishing time-varying delays

065004

Number 2

GENERAL PHYSICS

From the conservation laws to the Hamiltonian structures of discrete soliton systems Jian-bing Zhang, Jie Ji and Yu-qin Yao

AnAmplification international journal for experimental and theoretical physics of weak signals via the non-adiabatic regime of stochastic resonance in a bistable

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On eigenvalue problems in quantum mechanics Aparna Saha, Umapada Das and B Talukdar

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Exact spatiotemporal wave and soliton solutions to the generalized (3+1)-dimensional nonlinear Schrödinger equation with linear potential Nikola Z Petrović, Hussein Zahreddine and Milivoj R Belić

065002

ate

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Volume 83

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